Glu Mobile (GLUU) 10-K 26 Feb 21 2020 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2020	Feb. 18, 2021	Jun. 30, 2020
Document And Entity Information [Abstract]
Document Type	10-K
Document Annual Report	true
Document Transition Report	false
Document Period End Date	Dec. 31, 2020
Entity File Number	001-33368
Entity Registrant Name	Glu Mobile Inc
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	91-2143667
Entity Address, Address Line One	875 Howard Street, Suite 100
Entity Address, City or Town	San Francisco
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94103
City Area Code	415
Local Phone Number	800-6100
Title of 12(b) Security	Common Stock, par value $0.0001 per share
Trading Symbol	GLUU
Security Exchange Name	NASDAQ
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	true
Entity Shell Company	false
Entity Public Float			$ 1,364,594,790
Entity Common Stock, Shares Outstanding		174,821,822
Entity Central Index Key	0001366246
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	FY
Amendment Flag	false

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 364,396	$ 127,053
Accounts receivable, net	34,571	29,304
Prepaid royalties	12,831	15,347
Deferred royalties	6,924	5,067
Deferred platform commission fees	35,279	29,239
Prepaid expenses and other assets	9,071	8,629
Total current assets	463,072	214,639
Property and equipment, net	15,654	17,643
Operating lease right of use assets	31,461	35,170
Long-term prepaid royalties	20,626	26,879
Other long-term assets	5,315	2,733
Intangible assets, net	1,500	4,758
Goodwill	116,227	116,227
Total assets	653,855	418,049
Current liabilities:
Accounts payable and accrued liabilities	15,318	17,535
Accrued compensation	27,246	11,260
Accrued royalties	15,773	20,802
Short-term operating lease liabilities	4,693	3,528
Deferred revenue	117,672	97,629
Total current liabilities	180,702	150,754
Long-term accrued royalties	20,476	26,842
Long-term operating lease liabilities	34,565	37,351
Other long-term liabilities	1,018	15
Total liabilities	236,761	214,962
Commitments and contingencies (Note 8)
Stockholders' equity:
Preferred stock, $0.0001 par value; 5,000 shares authorized at December 31, 2020 and December 31, 2019; no shares issued and outstanding at December 31, 2020 and December 31, 2019
Common stock, $0.0001 par value; 250,000 shares authorized at December 31, 2020 and December 31, 2019; 173,743 and 147,778 shares issued and outstanding at December 31, 2020 and December 31, 2019	18	15
Additional paid-in capital	828,302	634,721
Accumulated other comprehensive loss	(61)	(37)
Accumulated deficit	(411,165)	(431,612)
Total stockholders' equity	417,094	203,087
Total liabilities and stockholders' equity	$ 653,855	$ 418,049

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares shares in Thousands	Dec. 31, 2020	Dec. 31, 2019
CONSOLIDATED BALANCE SHEETS
Preferred stock, par value	$ 0.0001	$ 0.0001
Preferred stock, shares authorized	5,000	5,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	250,000	250,000
Common stock, shares issued	173,743	147,778
Common stock, shares outstanding	173,743	147,778

CONSOLIDATED STATEMENTS OF OPER

CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
CONSOLIDATED STATEMENTS OF OPERATIONS
Revenue	$ 540,522	$ 411,381	$ 366,561
Cost of revenue:
Platform commissions, royalties and other	188,295	141,112	129,156
Impairment and amortization of intangible assets	3,258	4,387	9,119
Total cost of revenue	191,553	145,499	138,275
Gross profit	348,969	265,882	228,286
Operating expenses:
Research and development	119,718	95,127	95,174
Sales and marketing	177,245	140,298	113,860
General and administrative	31,491	23,216	31,667
Total operating expenses	328,454	258,641	240,701
Income/(loss) from operations	20,515	7,241	(12,415)
Interest and other income/(expense), net	1,071	2,101	(235)
Income/(loss) before income taxes	21,586	9,342	(12,650)
Income tax provision	(1,139)	(471)	(549)
Net income/(loss)	$ 20,447	$ 8,871	$ (13,199)
Net income/(loss) per common share - basic	$ 0.13	$ 0.06	$ (0.09)
Net income/(loss) per common share - diluted	$ 0.12	$ 0.06	$ (0.09)
Weighted average common shares outstanding:
Basic	162,521	145,838	141,402
Diluted	173,167	157,383	141,402

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME/(LOSS) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME/(LOSS)
Net income/(loss)	$ 20,447	$ 8,871	$ (13,199)
Other comprehensive income/(loss):
Foreign currency translation adjustments	(24)	(38)	7
Other comprehensive income/(loss)	(24)	(38)	7
Comprehensive income/(loss)	$ 20,423	$ 8,833	$ (13,192)

CONSOLIDATED STATEMENTS OF STOC

CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Common stock	Additional Paid-In Capital	Accumulated other comprehensive income (loss)	Accumulated DeficitCumulative effect adjustment from adoption of ASU 2014-09	Accumulated Deficit	Cumulative effect adjustment from adoption of ASU 2014-09	Total
Beginning balance at Dec. 31, 2017	$ 14	$ 589,962	$ (6)	$ 8,826	$ (436,110)	$ 8,826	$ 153,860
Beginning balances (in shares) at Dec. 31, 2017	138,745
Net income (loss)					(13,199)		(13,199)
Stock-based compensation expense		24,592					24,592
Issuance of common stock upon exercise of stock options		6,922					6,922
Issuance of common stock upon exercise of stock options (in shares)	2,721
Taxes paid related to net share settlement of equity awards		(7,097)					(7,097)
Taxes paid related to net share settlement of equity awards (in shares)	1,634
Issuance of common stock pursuant to Employee Stock Purchase Plan		2,356					2,356
Issuance of common stock pursuant to Employee Stock Purchase Plan (in shares)	770
Non-cash warrant expense		1,046					1,046
Other comprehensive income (loss)			7				7
Ending balance at Dec. 31, 2018	$ 14	617,781	1		(440,483)		177,313
Ending balances (in shares) at Dec. 31, 2018	143,870
Net income (loss)					8,871		8,871
Stock-based compensation expense		17,383					17,383
Issuance of common stock upon exercise of stock options	$ 1	4,553					4,554
Issuance of common stock upon exercise of stock options (in shares)	1,723
Taxes paid related to net share settlement of equity awards		(8,408)					(8,408)
Taxes paid related to net share settlement of equity awards (in shares)	1,457
Issuance of common stock pursuant to Employee Stock Purchase Plan		3,412					3,412
Issuance of common stock pursuant to Employee Stock Purchase Plan (in shares)	728
Other comprehensive income (loss)			(38)				(38)
Ending balance at Dec. 31, 2019	$ 15	634,721	(37)		(431,612)		203,087
Ending balances (in shares) at Dec. 31, 2019	147,778
Net income (loss)					20,447		20,447
Stock-based compensation expense		31,177					31,177
Issuance of common stock upon exercise of stock options	$ 1	19,462					19,463
Issuance of common stock upon exercise of stock options (in shares)	5,928
Issuance of common stock upon exercise of warrants (in shares)	115
Taxes paid related to net share settlement of equity awards		(12,674)					(12,674)
Taxes paid related to net share settlement of equity awards (in shares)	1,888
Issuance of common stock pursuant to Employee Stock Purchase Plan		3,845					3,845
Issuance of common stock pursuant to Employee Stock Purchase Plan (in shares)	784
Issuance of common stock upon follow-on public offering, net of issuance costs	$ 2	151,771					151,773
Issuance of common stock upon follow-on public offering, net of issuance costs (in shares)	17,250
Other comprehensive income (loss)			(24)				(24)
Ending balance at Dec. 31, 2020	$ 18	$ 828,302	$ (61)		$ (411,165)		$ 417,094
Ending balances (in shares) at Dec. 31, 2020	173,743

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Cash flows from operating activities:
Net income/(loss)	$ 20,447	$ 8,871	$ (13,199)
Adjustments to reconcile net income/(loss) to net cash provided by operating activities:
Stock-based compensation	31,809	17,383	24,592
Depreciation	5,421	4,225	3,855
Non-cash lease expense	4,105	3,348
Impairment and amortization of intangible assets	3,258	4,387	9,119
Warrant expense			1,046
Other non-cash adjustments	(212)	613	1,806
Changes in operating assets and liabilities:
Accounts receivable	(4,891)	(1,975)	7,028
Prepaid royalties	(2,759)	389	(947)
Deferred royalties	(1,857)	(657)	(835)
Deferred platform commission fees	(6,040)	(3,377)	(5,416)
Prepaid expenses and other assets	(3,122)	(1,957)	1,345
Accounts payable, accrued restructuring, and other accrued liabilities	773	3,090	(10,709)
Accrued compensation	10,045	(6,636)	(2,707)
Accrued royalties	(52)	(1,029)	(947)
Deferred revenue	20,043	11,893	17,947
Other long-term liabilities	1,003	(365)	308
Operating lease liabilities	(1,919)	(3,022)
Net cash provided by operating activities	76,052	35,181	32,286
Cash flows from investing activities:
Purchase of property and equipment	(7,064)	(5,283)	(3,362)
Proceeds from divestiture of Moscow studio			2,726
Other investing activities		(155)
Net cash used in investing activities	(7,064)	(5,438)	(636)
Cash flows from financing activities:
Proceeds from follow-on public offering, net of issuance costs	151,773
Proceeds from exercise of stock options and purchases under the ESPP	23,308	7,965	9,278
Taxes paid related to net share settlement of equity awards	(6,733)	(8,408)	(7,097)
Net cash provided by/(used in) financing activities	168,348	(443)	2,181
Effect of exchange rate changes on cash	7	(191)	(253)
Net increase in cash, cash equivalents and restricted cash	237,343	29,109	33,578
Cash, cash equivalents and restricted cash at beginning of period	127,053	97,944	64,366
Cash, cash equivalents and restricted cash at end of period	364,396	127,053	97,944
Reconciliation of cash, cash equivalents, and restricted cash to the condensed consolidated balance sheets
Total cash, cash equivalents, and restricted cash	364,396	97,944	97,944
Supplemental disclosures of cash flow information
Purchases of property and equipment included in accounts payable and accrued liabilities and other current liabilities	2	3,633	1,101
Income taxes paid	$ 657	$ 723	$ 382

THE COMPANY AND SUMMARY OF SIGN

THE COMPANY AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	12 Months Ended
	Dec. 31, 2020
THE COMPANY AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
THE COMPANY AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	NOTE 1 — THE COMPANY AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES ​ The Company ​ Glu Mobile Inc. (the “Company” or “Glu”) was incorporated in Nevada in May 2001 and reincorporated in the state of Delaware in March 2007. The Company develops, publishes, and markets a portfolio of games designed for users of smartphones and tablet devices who download and make purchases within its games through direct-to-consumer digital storefronts, such as the Apple App Store, Google Play Store, and others (“Digital Storefronts”). The Company creates games based on its own original brands, as well as third-party licensed brands, properties and other content. ​ Basis of Presentation ​ The Company's consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States (“U.S. GAAP”). ​ Principles of Consolidation ​ The consolidated financial statements include the accounts of the Company and its wholly owned subsidiaries. All intercompany balances and transactions have been eliminated on consolidation. ​ Use of Estimates ​ The preparation of financial statements in conformity with U.S. GAAP requires the Company’s management to make judgments, assumptions and estimates that affect the amounts reported in its consolidated financial statements and accompanying notes. Management bases its estimates on historical experience and on various other assumptions it believes to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities. Estimates and assumptions reflected in the consolidated financial statements include, but are not limited to, estimation of the average playing period of paying users associated with durable virtual items, the allowance for doubtful accounts, useful lives of property and equipment and intangible assets, valuation and realizability of deferred tax assets and uncertain tax positions, fair value of stock awards issued, fair value of warrants issued, accounting for business combinations, evaluating goodwill, long-lived assets for impairment, and realization of prepaid royalties and fair value of investments. Actual results may differ from these estimates due to risks and uncertainties, and these differences may be material, including uncertainty in the current economic environment due to the novel strain of coronavirus, SARS-CoV-2 (“COVID-19”) pandemic. Management will continue to actively monitor the impact of the COVID-19 pandemic on the Company’s assumptions and estimates. ​ Revenue Recognition ​ The Company generates revenue through in-application purchases (“in-app purchases”) within its games on smartphones and tablet devices, such as Apple’s iPhone and iPad, and mobile devices utilizing Google’s Android operating system. Users can download the Company’s free-to-play games ​ The Company adopted Accounting Standard Codification Topic 606, Revenue from Contracts with Customers, (“ASC 606”) and identifies the payment terms related to these services, (ii) the contract has commercial substance and, (iii) the Company determines that collection of substantially all consideration for services that are transferred is probable based on the customer’s intent and ability to pay the promised consideration. The Company applies judgment in determining the customer’s ability and intention to pay, which is based on a variety of factors including the customer’s historical payment experience or, in the case of a new customer, published credit and financial information pertaining to the customer. ​ ASC 606 requires an entity to disclose the revenue recognized in the reporting period from performance obligations satisfied (or partially satisfied) in previous periods (for example, due to changes in transaction price). Revenue recognized relating to performance obligations satisfied in prior periods was $0 for the year ended December 31, 2020 and December 31, 2019, respectively. The Company elects to use the practical expedient under 606-10-50-14 which states an entity need not disclose the information in paragraph 606-10-50-13 for a performance obligation if the following criteria are met: ​ 1. the performance obligation is part of a contract that has an original expected duration of one year or less; and 2. the entity recognizes revenue from the satisfaction of the performance obligation in accordance with paragraph 606-10-55-18 (right to invoice). ​ Since all of the Company’s contracts have an original expected duration of one year or less, the Company elects to use this practical expedient and does not disclose the aggregate transaction price allocated to unsatisfied or partially satisfied performance obligations. ​ In-App Purchases Users can download the Company’s free-to-play games within the Digital Storefronts and pay to acquire virtual currency, which can be redeemed in the game for virtual goods, or virtual goods directly (together, defined as “virtual items”) to enhance their game-playing experience. The Company sells both consumable and durable virtual items and receives reports from the Digital Storefronts, which breakdown the various purchases made from the Company’s games over a given time period. The Company reviews these reports and determines on a per-item basis whether the purchase was a consumable virtual item or a durable virtual item. Consumable virtual items are items that are consumed at a predetermined time or otherwise have limitations on repeated use. Durable virtual items are items, such as furniture, clothes, etc. that are accessible to the player over an extended period of time and that remain in the game for as long as the player continues to play. ​ The initial download of the mobile game from the Digital Storefront does not create a contract under ASC 606 because of the lack of commercial substance; however, the separate election by the player to make an in-application purchase satisfies the criterion thus creating a contract under ASC 606. The Company has identified the following performance obligations in these contracts: 1. Ongoing game related services such as hosting of game play, storage of customer content, when and if available content updates, maintaining the virtual currency management engine, tracking gameplay statistics, matchmaking as it relates to multiple player gameplay, etc. 2. Obligation to the paying player to continue displaying and providing access to the virtual items within the game. ​ Neither of these obligations are considered distinct since the actual mobile game and the related ongoing services are both required to purchase and benefit from the related virtual items. As such, the Company’s performance obligations represent a single combined performance obligation which is to make the game and the ongoing game related services available to the players. The transaction price, which is the amount paid for the virtual items by the player, is allocated entirely to the single combined performance obligation. The Company recognizes revenue for durable virtual items over the estimated average playing period of paying users on a per title basis. The Company’s revenue from consumable virtual items has been insignificant over the previous three years. The Company has estimated the useful life of a paying user between four ​ Advertisements and Offers The Company has relationships with certain advertising service providers for advertisements within its mobile games. Revenue from these advertising service providers is generated through impressions, clickthroughs, offers and banner ads. Offers are the type of advertisements where the players are rewarded with virtual currency for completing specified actions, such as downloading another application, watching a short video, subscribing to a service or completing a survey. The Company has determined the advertising buyer to be its customer and displaying the advertisements within the mobile games is identified as the single performance obligation. Revenue from advertisements and offers are recognized at the point-in-time the advertisements are displayed in the game or the offer has been completed by the user as the customer simultaneously receives and consumes the benefits provided from these services. ​ Other Estimates and Judgments The Company computes its estimated average playing period of paying users at least twice each year. It has examined the playing patterns of paying users across a representative sample of its games across various genres. The Company uses the “survival analysis” model to estimate the average playing period for paying users. This model provides for a singular approach to estimating the average playing period of paying users on a title by title basis for the Company’s diverse portfolio of games. It is a statistical model that analyzes time duration until one or more events happens and is commonly used in various industries for estimating lifespans. The Company believes this is an appropriate model to estimate the average playing period of paying users for its titles as this model statistically estimates the average playing period of each title by analyzing the historical behavior patterns of paying users. ​ This model requires the stratification of user data into active and inactive paying users on a per title basis. Active users are those who are active in the game for the past 30 days as of the evaluation date. The remaining users are considered inactive and deemed to have churned from the game. These users are treated mathematically differently in the model than those who are still active. A distribution curve is then fit to the user data to estimate the average playing period of paying users on a per title basis. ​ The Company has selected a threshold of 120 days from the commercial launch of a title as the minimum number of days of data required for this model. This threshold was deemed to be appropriate as the Company tested the model using lower thresholds which resulted in inconsistencies in the estimate of the average playing period of paying users. For new titles with less than 120 days of data that share similar attributes with an existing title and/or prequel titles, the average playing period is determined based on the average playing period of that existing title or prequel title, as applicable. For all other titles with less than 120 days of data, the average playing period is determined based on the average playing period of all other remaining existing titles. ​ While the Company believes its estimates to be reasonable based on available game player information, it may revise such estimates in the future if a titles’ user characteristics change. Any adjustments arising from changes in the estimates of the average playing period for paying users would be applied to the current quarter and prospectively on the basis that such changes are caused by new information that indicates a change in user behavior patterns compared to historical titles. Any changes in the Company’s estimates of the useful life of virtual items in a certain title may result in revenue being recognized on a basis different from prior periods’ and may cause its operating results to fluctuate. ​ Principal Agent Considerations ​ The Company evaluated its Digital Storefront and advertising service provider agreements under ASC 606 in order to determine if it is acting as the principal or as an agent when selling virtual items or advertisements within its games. The Company primarily uses Digital Storefronts for distributing its smartphone games and for enabling players to purchase virtual items and advertising service providers to serve advertisements within its games. The Company evaluated the following factors to assess whether it controls each specified good or service before that good or service is transferred to the customer: ​ ● the party responsible for the fulfillment of the virtual items, game related services, or serving of advertisements; ● the party having the discretion to set pricing with the end-users; and ● the party having inventory risk before the specified good or service have been transferred to a customer. ​ Based on the evaluation of the above indicators, the Company determined that it has control of the services before they are transferred to the end-user. Thus, the Company is generally acting as a principal and is the primary obligor to end-users for games distributed through Digital Storefronts and advertisements served through its advertising service providers. Therefore, the Company recognizes revenue related to these arrangements on a gross basis, when the necessary information about the gross amounts or platform fees charged, before any adjustments, are made available by the Digital Storefronts and advertising service providers. In situations where the price paid by the end-user of the advertising service provider is not known, the Company accounts for these transactions on a net basis. ​ Deferred Platform Commissions and Royalties ​ Digital Storefronts retain platform commissions and fees on each purchase made by the paying players through the Digital Storefront. The Company is also obligated to pay ongoing licensing fees in the form of royalties related to the games developed based on or significantly incorporating licensed brands, properties or other content, and the Company plans to incorporate additional licensed content in some of its own originally branded games. As revenue from sales to paying players through Digital Storefronts are deferred, the related direct and incremental platform commissions and fees as well as third-party royalties are also deferred on the consolidated balance sheets. The deferred platform commissions and royalties are recognized in the consolidated statements of operations in “Cost of revenue” in the period in which the related sales are recognized as revenue. ​ Cash and Cash Equivalents ​ Cash and cash equivalents consist of cash on hand and money market funds. The Company considers all investments purchased with original maturities of three months or less from the date of purchase to be cash equivalents. The Company deposits cash and cash equivalents with financial institutions that management believes are of high credit quality. Deposits held with financial institutions often exceed the amount of insurance on these deposits. ​ Concentration of Credit Risk ​ Financial instruments that potentially subject the Company to a concentration of credit risk consist of cash, cash equivalents and accounts receivable. ​ ​ The following table summarizes the revenue from customers or aggregate purchases through Digital Storefronts in excess of 10% of the Company’s revenue: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ ​ 2020 2019 2018 Apple ​ 56.2 % 54.4 % 54.7 % Google ​ 32.9 % 33.5 % 31.3 % ​ At December 31, 2020, Apple Inc. (“Apple”), Google Inc. (“Google”), and Tapjoy Inc. (“Tapjoy”) accounted for 42.7%, 28.8%, and 22.0%, respectively, of total accounts receivable. At December 31, 2019, Apple, Google and Tapjoy accounted for 47.2%, 28.5%, and 17.8%, respectively, of total accounts receivable. No other customer represented more than 10% of the Company’s total accounts receivable as of these dates. ​ Fair Value ​ Accounting Standard Codification 820 Fair Value Measurements and Disclosures ​ Level 1 ​ Level 2 ​ Level 3 ​ Foreign Currencies ​ ​ Cumulative foreign currency translation adjustments include any gain or loss associated with the translation of a subsidiary’s financial statements when the functional currency of a subsidiary is the local currency. If the Company disposes of any of its subsidiaries, any cumulative translation gains or losses would be realized and recorded in other income (expense) within the Company’s consolidated statement of operations in the period during which the disposal occurs. If the Company determines that there has been a change in the functional currency of a subsidiary from a local currency to the U.S. Dollar, any translation gains or losses arising after the date of change would be included in interest and other income/(expense), net within the Company’s consolidated statement of operations. ​ Prepaid or Guaranteed Licensor Royalties ​ The Company’s royalty expenses consist of fees that it pays to content owners for the use of their brands, properties and other licensed content, including trademarks and copyrights, in the development of the Company’s games. Royalty-based obligations are either paid in advance and capitalized on the balance sheet as prepaid royalties or accrued as incurred and subsequently paid. These royalty-based obligations are expensed to cost of revenue at the greater of the revenue derived from the relevant game multiplied by the applicable contractual rate or an effective royalty rate based on expected net product sales. ​ The Company’s contracts with some licensors include minimum guaranteed royalty payments, which are payable regardless of the ultimate revenue generated from end users. In accordance with Accounting Standard Codification 440-10 Commitments accrued royalties on the Company’s consolidated balance sheet. When no significant performance remains with the licensor, the Company initially records each of these guarantees as an asset and as a liability at the contractual amount. When significant performance remains with the licensor, the Company records royalty payments as an asset when actually paid and as a liability when incurred, rather than upon execution of the contract. The classification of minimum royalty payment obligations between long-term and short-term is determined based on the expected timing of recoupment of earned royalties calculated on projected revenue for the licensed IP games. ​ Each quarter, the Company evaluates the realization of its prepaid royalties as well as any recognized guarantees not yet paid to determine amounts that it deems unlikely to be realized through product sales. The Company uses estimates of revenue, cash flows and net margins to evaluate the future realization of prepaid royalties, license fees, and guarantees. This evaluation considers multiple factors such as the term of the agreement, forecasted demand, game life cycle status, game development plans, and current and anticipated sales levels, as well as other qualitative factors such as the success of similar games and similar genres on mobile devices published by the Company and its competitors other game platforms (e.g., consoles and personal computers) utilizing the intellectual property. To the extent that this evaluation indicates that the remaining prepaid and guaranteed royalty payments are not recoverable, the Company records an impairment charge to cost of revenue in the period in which impairment is indicated. related to prepaid guaranteed royalties for certain of its celebrity license agreements, and certain other prepaid royalties Goodwill and Intangible Assets ​ In accordance with Accounting Standard Codification 350 Intangibles-Goodwill and Other th ​ Qualitative assessment ​ Quantitative assessment ​ When necessary, to determine the reporting unit’s fair value under the quantitative approach, the Company uses a combination of income and market approaches, such as estimated discounted future cash flows of that reporting unit, multiples of earnings or revenue, and an analysis of recent sales or offerings of comparable entities. The Company also considers its market capitalization on the date of the analysis to ensure the reasonableness of the reporting unit’s fair value. ​ In 2020, 2019, and 2018, the Company did not ​ Purchased intangible assets with finite lives are amortized using the straight-line method over their useful lives ranging from three 360, Property, Plant and Equipment ​ Impairment of Long-Lived Assets ​ The Company evaluates its long-lived assets, including property and equipment and intangible assets with finite lives, for impairment whenever events or changes in circumstances indicate that the carrying value of these assets may not be recoverable. Factors considered important that could result in an impairment review include significant underperformance relative to expected historical or projected future operating results, significant changes in the manner of use of acquired assets, significant negative industry or economic trends, and a significant decline in the Company’s stock price for a sustained period of time. Impairment exists if the carrying amounts of such assets exceed the estimates of future undiscounted cash flows expected to be generated by such assets. Should an impairment exist, the impairment loss would be measured based on the excess carrying value of the asset over expected discounted future cash flows, or if applicable, the quoted market price from those assets. The Company has not recorded any such impairment charge during the years presented. ​ Property and Equipment ​ The Company states property and equipment at cost less accumulated depreciation and amortization. The Company computes depreciation or amortization using the straight-line method over the estimated useful lives of the respective assets or, in the case of leasehold improvements, the lease term of the respective assets, whichever is shorter. Cost of maintenance and repairs that do not improve or extend the lives of the respective assets are expensed as incurred. ​ The depreciation and amortization periods for the Company’s property and equipment are as follows: ​ ​ ​ ​ Computer equipment Three years ​ Computer software Two ​ Furniture and fixtures Three years ​ Leasehold improvements Shorter of the estimated useful life or remaining term of lease ​ ​ Internal Use Software ​ The Company capitalizes internal use software development costs in accordance with Accounting Standard Codification 350-40 Intangibles-Goodwill and Other-Internal Use Software Accounting Standards Update 2015-05 Cloud Computing Arrangements ​ Research and Development Costs ​ The Company charges costs related to research, design and development of products to research and development expense as incurred. The types of costs included in research and development expenses include personnel-related expenses such as salaries and benefits related to product development employees, third party development cost, contractor fees, and allocated facilities costs. ​ Software Development Costs ​ The Company applies the principles of Accounting Standard Codification 985-20 Software-Costs of Computer Software to Be Sold, Leased, or Otherwise Marketed ​ Stock-Based Compensation ​ The Company applies the fair value provisions of Accounting Standard Codification 718 Compensation-Stock Compensation ​ The cost of RSUs and PSUs is determined using the fair value of the Company’s common stock based on the quoted closing price of the Company’s common stock on the date of grant. Compensation cost for stock options, RSUs and performance-based awards with a single vesting date is amortized ratably over the requisite service period. For performance-based awards that have multiple vesting dates, the compensation cost is recognized ratably over the requisite service period for each tranche, whereby each vesting tranche is treated as a separate award for determining the requisite service period. The compensation cost for performance-based awards may be adjusted over the vesting period based on interim estimates of performance against the pre-set financial performance measures. ​ Advertising Expenses ​ The Company expenses the production costs of advertising, including direct response advertising, the first time the advertising takes place. Advertising expense was $146,207, $117,979, and $95,037 in the years ended December 31, 2020, 2019, and 2018, respectively. ​ Income Taxes ​ The Company accounts for income taxes in accordance with Accounting Standard Codification 740 Income Taxes ​ The Company accounts for uncertain tax positions in accordance with ASC 740, which requires companies to adjust their financial statements to reflect only those tax positions that are more-likely-than-not to be sustained. ASC 740 prescribes a comprehensive model for the financial statement recognition, measurement, presentation and disclosure of uncertain tax positions taken or expected to be taken in income tax returns. The Company’s policy is to recognize interest and penalties related to unrecognized tax benefits in income tax expense. ​ Comprehensive Income/(Loss) ​ Comprehensive income/(loss) consists of two components, net income/(loss) and other comprehensive income/(loss). Other comprehensive income/(loss) refers to revenue, expenses, gains and losses that under GAAP are recorded as an element of stockholders’ equity but are excluded from net income/(loss). The Company’s other comprehensive income/(loss) included foreign currency translation adjustments from those subsidiaries not using the U.S. Dollar as their functional currency, and a reclassification to net income/(loss) from the write-off of cumulative translation adjustment. ​ Operating Leases ​ Effective January 1, 2019, the Company adopted Accounting Standards Update (“ASU”) No. 2016-02, Leases (Topic 842) and its related amendments. According to ASC 842, the Company determines if an arrangement is a lease at inception. Its operating lease agreements are primarily for real estate space and are included within operating lease right of use (“ROU”) assets and operating lease liabilities on the consolidated balance sheets. ​ ROU assets represent the Company’s right to use an underlying asset for the lease term and operating lease liabilities represent its obligation to make lease payments arising from the lease. ROU assets and operating lease liabilities are recognized at the commencement date based on the present value of lease payments over the lease term. As the Company’s leases do not provide an implicit rate, the Company uses its incremental borrowing rate, determined as the rate it would have incurred to borrow based on its credit quality at the inception of the lease over a similar term and in the economic environment where the leased asset is located, to calculate the present value of lease payments. ROU assets also exclude lease incentives. Many of the Company’s lease agreements include options to extend the lease, which the Company does not include in the minimum lease terms unless they are reasonably certain to be exercised. Rental expense for lease payments related to operating leases is recognized on a straight-line basis over the lease term. ​ Certain of the Company’s lease agreements contain lease components (for example, fixed payments such as rent) and non-lease components such as common-area maintenance costs. Both of these types of provisions are accounted for as a single lease component. For such arrangements, there may be a variability in future lease payments as the amount of the non-lease components is typically revised from one period to the next. These variable lease payments, which are primarily comprised of common-area maintenance, utilities, and real estate taxes that are passed on from the lessor in proportion to the space leased by the Company within the entire building or building complex, are recognized in the period in which the obligation for those payments is incurred ​ For leases that have greater than 12-month lease term, ROU assets and lease liabilities are recognized on the consolidated balance sheet at commencement date based on the present value of remaining fixed lease payments. The Company considers only payments that are fixed and determinable at the time of commencement . Short-term leases with an initial term of 12 months or less are not recorded on the balance sheet. The Company combines fixed lease and non-lease components and account for them as a single lease component. ​ Recent Accounting Pronouncements ​ Recently Adopted Accounting Pronouncements ​ In June 2016, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2016-13, “Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments” , which requires the measurement and recognition of expected credit losses for financial assets held at amortized cost and replaces the existing incurred loss impairment model with an expected loss methodology, which will result in earlier recognition of credit losses. The ASU requires a cumulative-effect adjustment to retained earnings transition approach and is effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. The adoption of this standard did not have a material impact on the Company’s consolidated financial statements. ​ In January 2017, the FASB issued ASU No. 2017-04, Intangibles—Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment . This new accounting standard update simplifies the measurement of goodwill by eliminating the Step 2 impairment test. Step 2 measures a goodwill impairment loss by comparing the implied fair value of a reporting unit’s goodwill with the carrying amount of that goodwill. The new guidance requires an entity to compare the fair value of a reporting unit with its carrying amount and recognize an impairment charge for the amount by which the carrying amount exceeds the reporting unit’s fair value, limited to the amount of goodwill. Additionally, an entity should consider income tax effects from any tax deductible goodwill on the carrying amount of the reporting unit when measuring the goodwill impairment loss, if applicable. The new guidance becomes effective for goodwill impairment tests in fiscal years beginning after December 15, 2019. The adoption of this standard did not have a material impact on the Company’s consolidated financial statements. ​ In August 2018, the FASB issued ASU 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework – Changes to the Disclosure Requirements for Fair Value Measurement. This guidance adds, modifies and removes several disclosure requirements relative to the three levels of inputs used to measure fair value in accordance with Topic 820, Fair Value Measurement. This guidance is effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. The adoption of this standard did not have a material impact on the Company’s consolidated financial statements. ​ In August 2018, the FASB issued ASU 2018-15, Intangibles – Goodwill and Other – Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract . This guidance aligns the requirements for capitalizing implementation costs incurred in a hosting arrangement that is a service contract with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software. This guidance is effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. The adoption of this standard did not have a material impact on the Company’s consolidated financial statements. ​ Recently Issued Accounting Pronouncements Not Yet Adopted In December 2019, the FASB issued ASU 2019-12, Income Taxes (Topic 740) : Simplifying the Accounting for Income Taxes . In October 2020, the FASB issued ASU 2020-10, Codification Improvements

NET INCOME_(LOSS) PER SHARE

NET INCOME/(LOSS) PER SHARE	12 Months Ended
	Dec. 31, 2020
NET INCOME/(LOSS) PER SHARE
NET INCOME/(LOSS) PER SHARE	NOTE 2 — NET INCOME/(LOSS) PER SHARE ​ The Company computes basic net income/(loss) per share by dividing its net income/(loss) for the period by the weighted average number of common shares outstanding during the period. ​ Diluted net income per share is computed by dividing the net income attributable to common stockholders by the weighted-average number of common shares outstanding during the period, including potential dilutive common stock instruments. Diluted net loss per share is computed by dividing the net loss by the weighted-average number of common shares outstanding during each period, without consideration for common share equivalents as their effect would have been antidilutive. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ 2020 2019 2018 Net income/(loss) ​ $ 20,447 ​ $ 8,871 ​ $ (13,199) ​ Shares used to compute net income/(loss) per share: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted average shares used to compute basic net income/(loss) per share ​ ​ 162,521 ​ ​ 145,838 ​ ​ 141,402 ​ Dilutive potential common shares ​ ​ 10,646 ​ ​ 11,545 ​ ​ — ​ Weighted average shares used to compute diluted net income/(loss) per share ​ 173,167 ​ 157,383 ​ 141,402 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Basic net income/(loss) per share ​ $ 0.13 ​ $ 0.06 ​ $ (0.09) ​ Diluted net income/(loss) per share ​ $ 0.12 ​ $ 0.06 ​ $ (0.09) ​ ​ ​ The following equity awards outstanding at the end of each period presented have been excluded from the computation of net income/(loss) per share of common stock for the periods presented because including them would have had an anti-dilutive effect: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ 2020 2019 2018 Warrants to purchase common stock ​ ​ — ​ 1,292 ​ 1,600 Options to purchase common stock ​ ​ 592 ​ 2,303 ​ 18,491 Restricted stock units ("RSUs") ​ ​ 1,073 ​ ​ 659 ​ ​ 3,021 Performance stock options ("PSOs") ​ ​ — ​ ​ 2,369 ​ ​ 3,512 Performance stock units ("PSUs") ​ ​ — ​ ​ 38 ​ ​ 711 Employee stock purchase plan ("ESPP") ​ ​ — ​ 369 ​ 283 Total ​ ​ 1,665 ​ ​ 7,030 ​ ​ 27,618 (1) Outstanding PSOs and PSUs for which performance conditions have not been met as of the relevant reporting dates, have not been included in the calculation of the weighted average number of shares used to compute diluted net income/(loss) per share or in the table above. ​

REVENUE FROM CONTRACTS WITH CUS

REVENUE FROM CONTRACTS WITH CUSTOMERS	12 Months Ended
	Dec. 31, 2020
REVENUE FROM CONTRACTS WITH CUSTOMERS
REVENUE FROM CONTRACTS WITH CUSTOMERS	NOTE 3 – REVENUE FROM CONTRACTS WITH CUSTOMERS ​ Disaggregation of Revenue ​ The following table summarizes revenue from contracts with customers for the year ended December 31, 2020: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended ​ ​ December 31, ​ ​ 2020 ​ 2019 ​ 2018 In-App Purchases (over-time revenue recognition) ​ $ 481,279 ​ $ 360,598 ​ $ 316,157 Advertisements and offers (point-in-time revenue recognition) ​ ​ 59,046 ​ ​ 50,728 ​ ​ 50,121 Other (point-in-time revenue recognition) ​ ​ 197 ​ ​ 55 ​ ​ 283 Total revenue ​ $ 540,522 ​ $ 411,381 ​ $ 366,561 ​ The Company operates in a single reportable segment. In the table above, revenue is disaggregated by type of revenue stream, indicating whether it is recognized over-time or at a point-in-time. ​ Contract Balances ​ The following table provides information about receivables, contracts assets, and contract liabilities from contracts with customers: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2020 ​ December 31, 2019 Receivables, which are included in accounts receivable, net $ 34,571 ​ $ 29,304 Contract liabilities, which are included in deferred revenue 117,672 ​ 97,629 ​ The Company receives payments from customers based on billing terms established in the Company’s contracts. Contract asset relates to the Company’s right to consideration for its completed performance under the contract. At December 31, 2020 and December 31, 2019, there were no contract assets recorded in the Company’s consolidated balance sheet. Accounts receivable are recorded when the right to consideration becomes unconditional. ​ Deferred revenue relates to payments received in advance of performance under the contract. Deferred revenue is recognized as revenue as the Company performs under the contract. The Company had $97,629 in deferred revenue as of December 31, 2019, which was all earned in the year ended December 31, 2020. The Company had $85,736 in deferred revenue as of December 31, 2018, which was all earned in the year ended December 31, 2019.

FAIR VALUE MEASUREMENTS

FAIR VALUE MEASUREMENTS	12 Months Ended
	Dec. 31, 2020
FAIR VALUE MEASUREMENTS
FAIR VALUE MEASUREMENTS	NOTE 4 — FAIR VALUE MEASUREMENTS ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Level 1 Level 2 Level 3 December 31, 2020 Financial Assets ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash and cash equivalents ​ $ 364,396 ​ $ — ​ $ — ​ $ 364,396 ​ Other investments ​ ​ — ​ ​ — ​ ​ 1,565 ​ ​ 1,565 ​ Total financial assets ​ $ 364,396 ​ $ — ​ $ 1,565 ​ $ 365,961 ​ ​ As of December 31, 2019, the Company’s financial assets and financial liabilities are presented below at fair value and were classified within the fair value hierarchy as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Level 1 Level 2 Level 3 December 31, 2019 Financial Assets ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash and cash equivalents ​ $ 127,053 ​ $ — ​ $ — ​ $ 127,053 Other investments ​ ​ — ​ ​ — ​ ​ 1,565 ​ ​ 1,565 Total financial assets ​ $ 127,053 ​ $ — ​ $ 1,565 ​ $ 128,618 ​ The Company’s cash and cash equivalents, which were held in operating bank accounts and money market funds, are classified within Level 1 of the fair value hierarchy because they are valued using quoted market prices, broker or dealer quotations or alternative pricing sources with reasonable levels of price transparency. The carrying value of accounts receivable and payables approximates fair value due to the short time to expected payment or receipt of cash. The carrying value of other investments approximates fair value, as there have been no events or changes in circumstances that would have had a significant effect on the fair value of these investments at December 31, 2020.

BALANCE SHEET COMPONENTS

BALANCE SHEET COMPONENTS	12 Months Ended
	Dec. 31, 2020
BALANCE SHEET COMPONENTS
BALANCE SHEET COMPONENTS	NOTE 5 — BALANCE SHEET COMPONENTS ​ Accounts Receivable, Net ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ 2020 2019 Accounts receivable ​ $ 34,571 ​ $ 29,304 ​ Less: Allowance for doubtful accounts ​ — ​ — ​ Accounts receivable, net ​ $ 34,571 ​ $ 29,304 ​ ​ Accounts receivable include amounts billed and unbilled as of the respective balance sheet dates, but net of platform commissions to the Digital Storefronts. The Company had no bad debts as of the years ended December 31, 2020, 2019, and 2018. ​ Property and Equipment, Net ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ 2020 2019 Computer equipment ​ $ 10,559 ​ $ 9,079 ​ Furniture and fixtures ​ 3,303 ​ 2,201 ​ Software ​ 3,847 ​ 3,612 ​ Leasehold improvements ​ 16,498 ​ 16,121 ​ Total ​ 34,207 ​ 31,013 ​ Less: Accumulated depreciation and amortization ​ (18,553) ​ (13,370) ​ Property and equipment, net ​ $ 15,654 ​ $ 17,643 ​ ​ Depreciation for the years ended December 31, 2020, 2019, and 2018 was $5,421, $4,225, and $3,855, respectively.

GOODWILL AND INTANGIBLE ASSETS

GOODWILL AND INTANGIBLE ASSETS	12 Months Ended
	Dec. 31, 2020
GOODWILL AND INTANGIBLE ASSETS
GOODWILL AND INTANGIBLE ASSETS	NOTE 6 — GOODWILL AND INTANGIBLE ASSETS ​ Intangible Assets ​ The following table sets forth carrying amounts and accumulated amortization expense of acquired intangible assets that are not already fully amortized : ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2020 ​ December 31, 2019 ​ Estimated Gross Accumulated Net Gross Accumulated Net ​ ​ Useful ​ Carrying ​ Amortization ​ Carrying ​ Carrying ​ Amortization ​ Carrying ​ ​ Life ​ Value ​ Expense ​ Value ​ Value ​ Expense ​ Value Intangible assets amortized to cost of revenue: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Titles, content and technology 3 - 5 yrs. ​ $ 21,117 ​ $ (19,617) ​ $ 1,500 ​ $ 21,117 ​ $ (16,359) ​ $ 4,758 ​ ​ ​ ​ ​ $ 21,117 ​ $ (19,617) ​ $ 1,500 ​ $ 21,117 ​ $ (16,359) ​ $ 4,758 ​ ​ Acquisition-related intangibles included in the above table are finite-lived and are being amortized on a straight-line basis over their estimated lives, which approximate the pattern in which the economic benefits of the intangible assets are realized. The Company has included amortization of acquired intangible assets directly attributable to revenue-generating activities in cost of revenue. ​ During the years ended December 31, 2020 and 2019, the Company recorded amortization expense in cost of revenue of $3,258 and $4,387, respectively. During the year ended December 31, 2018, the Company recorded amortization and impairment expense in cost of revenue of $9,119. As of December 31, 2020, the Company expects to fully amortize its intangible assets in 2021. ​ Goodwill ​ The Company had $116,227 in goodwill as of December 31, 2020 and December 31, 2019, respectively. ​ During the third quarters of fiscal 2020 and 2019, the Company performed the qualitative impairment assessment for its reporting unit. Based on the assessment, the Company concluded that it was more likely than not that the fair value of the reporting unit was greater than its carrying amount, and as a result, it did not proceed with the quantitative impairment assessment. Accordingly, the Company did not recognize an impairment of goodwill during the years ended December 31, 2020 and December 31, 2019.

LEASES

LEASES	12 Months Ended
	Dec. 31, 2020
LEASES
LEASES	NOTE 7 — LEASES ​ The Company currently leases real estate space under non-cancelable operating lease agreements for its corporate headquarters in San Francisco, California and its operations in Toronto, Canada, Hyderabad, India, Foster City, California, Burlingame, California and Orlando, Florida. These operating leases have remaining lease terms ranging from 4 months to 6.92 years, some of which include the option to extend the lease, with the longest extension option being 6 years . ​ The Company does not include any of its renewal options when calculating its lease liability as the Company is not reasonably certain whether it will exercise these renewal options at this time. Rent expense for the year ended December 31, 2020, 2019, and 2018 was $6,307 , $5,311 , and $5,759 , respectively ​ The future minimum lease payments to be paid under noncancelable leases in effect at December 31, 2020, are as follows: ​ ​ ​ ​ ​ ​ ​ Operating Year Ending December 31, Leases 2021 ​ 7,129 2022 ​ 7,026 2023 ​ ​ 6,980 2024 ​ ​ 5,332 2025 and thereafter ​ ​ 22,335 Total lease payments ​ $ 48,802 Less: imputed interest ​ ​ (9,544) Total ​ $ 39,258 ​ Supplemental information related to the Company’s leases for the year ended December 31, 2020 is as follows: ​ ​ ​ ​ ​ ​ December 31, 2020 ​ Weighted average remaining lease term ​ 6.61 yrs. Weighted average discount rate ​ 6.7 % ​ ​ ​ ​ ​ ​ ​ ​ Year Ended ​ December 31, 2020 Cash paid for amounts included in the measurement of lease liabilities: ​ ​ ​ Operating cash outflow from operating leases ​ $ 4,751 ​ ​ ​ ​ ​ ​ ​ ​ Year Ended ​ December 31, 2020 Right of use assets obtained in exchange for new lease obligations: ​ ​ ​ Operating leases ​ $ 407 ​

COMMITMENTS AND CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	12 Months Ended
	Dec. 31, 2020
COMMITMENTS AND CONTINGENCIES
COMMITMENTS AND CONTINGENCIES	NOTE 8 — COMMITMENTS AND CONTINGENCIES ​ Minimum Guaranteed Royalties and Developer Commitments ​ The Company has entered into license and publishing agreements with various celebrities, athletes, sports and entertainment organizations, and other well-known brands and properties ​ At December 31, 2020, future unpaid minimum guaranteed royalty commitments were as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Future ​ ​ Minimum ​ ​ Guarantee Year Ending December 31, Commitments 2021 ​ 9,060 2022 ​ ​ 6,881 2023 ​ ​ 6,716 2024 ​ ​ 6,150 Total ​ $ 28,807 ​ The amounts represented in the table above reflect the Company’s minimum cash obligations for the respective calendar years, but do not necessarily represent the periods in which they will be expensed in the Company’s consolidated financial statements. ​ Licensor commitments include $28,807 of commitments due to licensors that have been recorded in current and long-term liabilities and a corresponding amount in current and long-term assets because payment is not contingent upon performance by the licensor. The classification of commitments between long-term and short-term is determined based on the timing of recoupment of earned royalties calculated on projected revenue for the licensed intellectual property games. ​ Income Taxes ​ As of December 31, 2020, unrecognized tax benefits have been netted against deferred tax assets and potential interest and penalties are classified within “other long-term liabilities” on the Company’s consolidated balance sheets. ​ Indemnification Arrangements ​ The Company has entered into agreements under which it indemnifies each of its officers and directors during his or her lifetime for certain events or occurrences while the officer or director is or was serving at the Company’s request in that capacity. The maximum potential amount of future payments the Company could be required to make under these indemnification agreements is unlimited; however, the Company has a director and officer insurance policy that limits its exposure and enables the Company to recover a portion of any future amounts paid. ​ In the ordinary course of its business, the Company includes standard indemnification provisions in most of its commercial agreements with Digital Storefronts and licensors. Pursuant to these provisions, the Company generally indemnifies these parties for losses suffered or incurred in connection with its games, including as a result of intellectual property infringement, viruses, worms and other malicious software, and legal or regulatory violations. The term of these indemnity provisions is generally perpetual after execution of the corresponding license agreement, and the maximum potential amount of future payments the Company could be required to make under these provisions is often unlimited. To date, the Company has not incurred costs to defend lawsuits or settle indemnified claims of these types. As a result, the Company believes the estimated fair value of these indemnity provisions is minimal. ​ Contingencies ​ From time to time, the Company is subject to various claims, complaints and legal actions in the normal course of business. The Company assesses its potential liability by analyzing specific litigation and regulatory matters using available information. The Company’s estimate of losses is developed in consultation with inside and outside counsel, which involves a subjective analysis of potential results and outcomes, assuming various combinations of appropriate litigation and settlement strategies. After taking all of the above factors into account, the Company determines whether an estimated loss from a contingency should be accrued by assessing whether a loss is deemed reasonably probable and the amount can be reasonably estimated. The Company further determines whether an estimated loss from a contingency should be disclosed by assessing whether a material loss is deemed reasonably possible. Such disclosure will include an estimate of the additional loss or range of loss or will state that an estimate cannot be made. ​ On December 17, 2020, the Company filed a lawsuit in the United States District Court for the Western District of Texas, Waco Division, against Reworks Oy (“Reworks”). The complaint alleges that Reworks infringes at least one claim of U.S. Patent No. 10,504,297, the Company’s patent relating to systems and methods for providing competitive scene completion in a mobile gaming application. The Company is pursuing a judgment finding that Reworks has infringed the Company’s patent and is seeking injunctive relief, as well as monetary damages for past and ongoing infringement. The Company does not believe it is party to any currently pending litigation, the outcome of which is reasonably possible to have a material adverse effect on its operations, financial position or liquidity. However, the ultimate outcome of any litigation is uncertain and, regardless of outcome, litigation can have an adverse impact on the Company because of defense costs, potential negative publicity, diversion of management resources and other factors.

STOCKHOLDERS' EQUITY

STOCKHOLDERS' EQUITY	12 Months Ended
	Dec. 31, 2020
STOCKHOLDERS' EQUITY
STOCKHOLDERS' EQUITY	NOTE 9— STOCKHOLDERS’ EQUITY ​ Common Stock ​ At December 31, 2020, the Company was authorized to issue 250,000 shares of common stock. As of December 31, 2020, the Company had reserved 34,468 shares for future issuance under its stock plans and outstanding warrants. ​ Follow-on Public Offering ​ In June 2020, the Company completed a follow-on public offering of 17,250 shares of its common stock, which included an over-allotment option to purchase an additional 2,250 shares, at a public offering price of $9.25 per share (the “Offering”). The aggregate gross proceeds from the Offering, including the exercise of the over-allotment, were approximately $159,563, and net proceeds received after underwriting fees and offering expenses totaled approximately $151,773. The Company does not have specific uses of the net proceeds from the Offering but intends to use the net proceeds for working capital and other general corporate purposes, which may include potential acquisitions and strategic transactions. ​ ​ ​ ​ ​ ​ ​ Warrants to Purchase Common Stock ​ Warrants outstanding at December 31, 2020 were as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Number ​ Weighted ​ ​ ​ ​ ​ of Shares ​ Average ​ ​ ​ ​ ​ Outstanding ​ Exercise ​ Average ​ ​ ​ Under ​ Price per ​ Contractual ​ ​ ​ Warrant Share Term (Years) Warrants outstanding, December 31, 2019 ​ 1,600 ​ $ 4.61 ​ 5.44 ​ Exercised ​ (475) ​ $ 4.99 ​ 5.00 ​ Expired ​ (25) ​ $ 4.99 ​ 5.00 ​ Warrants outstanding, December 31, 2020 ​ 1,100 ​ $ 4.44 ​ 5.66 ​ ​ No expenses with respect to these warrants were recognized during the During the year ended December 31, 2018, the Company recorded $1,046 of non-cash warrant related expense in cost of revenue as the mobile games featuring these celebrities licensors were not expected to generate meaningful revenue over their lifetime. ​ The Company estimated the fair value of the warrants using the Black-Scholes valuation model and the weighted average assumptions noted in the following table: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ 2020 2019 2018 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Dividend yield ​ — % ​ — % ​ — % Risk-free interest rate ​ — % ​ — % ​ 2.53 % Expected volatility ​ — % ​ — % ​ 56.73 % Expected term (in years) ​ — ​ ​ — ​ ​ 3.51 ​ ​ Preferred Stock ​ At December 31, 2020, the Company was authorized to issue 5,000 shares of preferred stock. ​ ​

STOCK INCENTIVE AND OTHER BENEF

STOCK INCENTIVE AND OTHER BENEFIT PLANS	12 Months Ended
	Dec. 31, 2020
STOCK INCENTIVE AND OTHER BENEFIT PLANS
STOCK INCENTIVE AND OTHER BENEFIT PLANS	NOTE 10 — STOCK INCENTIVE AND OTHER BENEFIT PLANS ​ 2007 Equity Incentive Plan ​ In 2007, the Company’s Board of Directors adopted, and the Company’s stockholders approved, the 2007 Equity Incentive Plan (the “2007 Plan”). The 2007 Plan permits the Company to grant stock options, RSUs, PSUs, PSOs and other stock-based awards to employees, non-employee directors and consultants. ​ In April 2020, the Company’s Board of Directors approved, and in June 2020, the Company’s stockholders approved, the Sixth Amended and Restated 2007 Equity Incentive Plan (the “Sixth Amended 2007 Plan”). The Sixth Amended 2007 Plan included an increase of 7,000 shares in the aggregate number of shares of common stock authorized for issuance under the plan. As of December 31, 2020, 7,459 shares were available for future grants under the Sixth Amended 2007 Plan. ​ Performance-based equity awards ​ The Compensation Committee of the Company’s Board of Directors (the “Compensation Committee”) has awarded PSOs and/or PSUs to the Company’s executives and certain other employees. These performance-based awards are subject to the achievement of specified annual performance goals. They become eligible to vest only if the applicable performance goals are achieved and will vest only if the grantee remains employed with the Company through each applicable vesting date. The number of shares that may vest depend on the extent to which the Company achieves the specified annual performance goals. The fair value of these awards is estimated on the date of grant. The PSOs have a contractual term of 10 years. If the performance goals are not met as of the end of the performance period, no compensation expense is recognized, and any previously recognized expense is reversed. The expected cost is based on the awards that are probable to vest and is recognized over the service period. ​ 2007 Employee Stock Purchase Plan ​ In 2007, the Company’s Board of Directors adopted and the Company’s stockholders approved, the 2007 Employee Stock Purchase Plan (the “2007 Purchase Plan”). The Company initially reserved 667 shares of its common stock for issuance under the 2007 Purchase Plan. The 2007 Purchase Plan permits eligible employees, including employees of certain of the Company’s subsidiaries, to purchase common stock at a discount through payroll deductions during defined offering periods. The price at which the stock is purchased is equal to the lower of 85% of the fair market value of the common stock at the beginning of an offering period or after a purchase period ends. ​ In April 2017, the Company’s Board of Directors approved, and in June 2017, the Company’s stockholders approved the Amended and Restated 2007 Employee Stock Purchase Plan (the “Amended 2007 Purchase Plan”). The Amended 2007 Purchase Plan includes an increase of 4,000 shares in the aggregate number of shares of common stock authorized for issuance under the plan and removal of the expiration date of the plan. ​ As of December 31, 2020, 2,003 shares were available for issuance under the 2007 Purchase Plan. ​ 2018 Equity Inducement Plan ​ In April 2018, the Compensation Committee of the Company’s Board of Directors adopted the 2018 Equity Inducement Plan (the “2018 Plan”). The 2018 Plan replaced the Company’s 2008 Equity Inducement Plan that expired by its terms in March 2018, and is intended to augment the shares available for issuance under the Sixth Amended 2007 Plan. The Company did not seek stockholder approval for the 2018 Plan. As such, awards under the 2018 Plan will be granted in accordance with Nasdaq Listing Rule 5635(c)(4) and only to persons not previously considered an employee or director of the Company, or following a bona fide period of non-employment, as an inducement material to such individuals entering into employment with the Company. The Company initially reserved 400 shares of common stock for issuance under the 2018 Plan. ​ As of December 31, 2020, 194 shares were reserved for future grants under the 2018 Plan. ​ RSU Activity A summary of the Company’s RSU activity is as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted ​ Weighted ​ ​ ​ ​ ​ Number of ​ Average ​ Average Remaining ​ ​ Aggregate ​ ​ Units ​ Grant Date ​ Contractual ​ ​ Intrinsic ​ Outstanding Fair Value ​ Term (Years) ​ ​ Value Awarded and unvested, December 31, 2017 ​ 5,812 ​ $ 2.96 ​ ​ ​ ​ ​ Granted ​ 278 ​ $ 5.90 ​ ​ ​ ​ ​ Vested ​ (2,648) ​ $ 3.24 ​ ​ ​ ​ ​ Forfeited ​ (421) ​ $ 2.71 ​ ​ ​ ​ ​ Awarded and unvested, December 31, 2018 ​ 3,021 ​ $ 3.01 ​ ​ ​ ​ ​ Granted ​ 2,936 ​ $ 6.84 ​ ​ ​ ​ ​ Vested ​ (1,688) ​ $ 3.27 ​ ​ ​ ​ ​ Forfeited ​ (318) ​ $ 4.17 ​ ​ ​ ​ ​ Awarded and unvested, December 31, 2019 3,951 ​ $ 5.66 ​ ​ ​ ​ ​ Granted (1) 4,635 ​ $ 7.29 ​ ​ ​ ​ ​ Vested (1,832) ​ $ 4.92 ​ ​ ​ ​ ​ Forfeited (486) ​ $ 6.15 ​ ​ ​ ​ ​ Awarded and unvested, December 31, 2020 6,268 ​ $ 7.04 ​ 1.62 ​ $ 56,478 ​ (1) As of December 31, 2020, granted awards included 293 unvested RSUs with an intrinsic value of $2,638, for which the Company and certain employees reached mutual understanding of the awards key terms and conditions in February 2021. Such awards were legally granted in November 2020. PSU Activity The following table summarizes the Company’s PSU activity: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted ​ Weighted ​ ​ ​ ​ ​ Number of ​ Average ​ Average Remaining ​ ​ Aggregate ​ ​ Units ​ Grant Date ​ Contractual ​ ​ Intrinsic ​ Outstanding Fair Value ​ Term (Years) ​ ​ Value Awarded and unvested, December 31, 2017 ​ 661 ​ $ 3.59 ​ ​ ​ ​ ​ Granted ​ 2,909 ​ $ 5.85 ​ ​ ​ ​ ​ Forfeited ​ (40) ​ $ 4.03 ​ ​ ​ ​ ​ Awarded and unvested, December 31, 2018 ​ 3,530 ​ $ 5.45 ​ ​ ​ ​ ​ Granted ​ 2,780 ​ $ 6.46 ​ ​ ​ ​ ​ Vested ​ (700) ​ $ 4.59 ​ ​ ​ ​ ​ Forfeited ​ (193) ​ $ 6.14 ​ ​ ​ ​ ​ Awarded and unvested, December 31, 2019 ​ 5,417 ​ $ 6.06 ​ ​ ​ ​ ​ Granted (1) ​ 1,432 ​ $ 9.53 ​ ​ ​ ​ ​ Vested ​ (1,509) ​ $ 5.64 ​ ​ ​ ​ ​ Forfeited ​ (1,436) ​ $ 6.78 ​ ​ ​ ​ ​ Awarded and unvested, December 31, 2020 ​ 3,904 ​ $ 7.22 ​ 1.38 ​ $ 35,178 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ PSUs expected to vest as of December 31, 2020 ​ 749 ​ $ 6.37 ​ 0.79 ​ $ 6,748 ​ (1) As of December 31, 2020, granted awards included 444 unvested PSUs with an intrinsic value of $3,997, for which the Company and certain employees reached mutual understanding of the awards key terms and conditions in February 2021. Such awards were legally granted in November 2020. ​ PSO Activity The following table summarizes the Company’s PSO activity: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted ​ Weighted ​ ​ ​ ​ ​ Number of ​ Average ​ Average Remaining ​ ​ Aggregate ​ ​ Shares ​ Exercise ​ Contractual ​ ​ Intrinsic ​ Outstanding Price ​ Term (Years) ​ ​ Value Balance as of December 31, 2017 ​ 4,170 ​ $ 3.59 ​ ​ ​ ​ ​ Granted ​ 2,737 ​ $ 5.87 ​ ​ ​ ​ ​ Forfeited ​ (151) ​ $ 3.59 ​ ​ ​ ​ ​ Balance as of December 31, 2018 ​ 6,756 ​ $ 4.51 ​ ​ ​ ​ ​ Exercised ​ (173) ​ $ 3.59 ​ ​ ​ ​ ​ Balance as of December 31, 2019 ​ 6,583 ​ $ 4.54 ​ ​ ​ ​ ​ Canceled ​ (1,377) ​ $ 6.18 ​ ​ ​ ​ ​ Exercised ​ (1,133) ​ $ 3.61 ​ ​ ​ ​ ​ Balance as of December 31, 2020 ​ 4,073 ​ $ 4.24 ​ 7.04 ​ $ 19,422 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ PSOs expected to vest as of December 31, 2020 ​ 992 ​ $ 4.93 ​ 7.30 ​ $ 4,054 PSOs exercisable at December 31, 2020 ​ 2,615 ​ $ 3.59 ​ 6.80 ​ $ 14,162 ​ Stock Option Activity ​ The following table summarizes the Company’s stock option activity: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Options Outstanding ​ ​ ​ ​ ​ ​ ​ Weighted Weighted ​ ​ ​ ​ Number ​ Average ​ Average Remaining ​ Aggregate ​ ​ of ​ Exercise ​ Contractual ​ Intrinsic ​ ​ Shares ​ Price ​ Term (Years) ​ Value Balances at December 31, 2017 16,932 $ 2.78 ​ ​ Options granted 6,092 $ 4.82 ​ ​ ​ ​ ​ ​ Options canceled (1,213) $ 3.54 ​ ​ ​ ​ ​ ​ Options exercised (3,320) $ 2.88 ​ ​ ​ ​ ​ ​ Balances at December 31, 2018 18,491 $ 3.39 ​ ​ ​ Options granted 815 $ 7.58 ​ ​ ​ ​ ​ ​ Options canceled (1,219) $ 4.73 ​ ​ ​ ​ ​ ​ Options exercised (1,799) $ 2.81 ​ ​ ​ ​ ​ ​ Balances at December 31, 2019 16,288 $ 3.56 ​ ​ ​ ​ ​ Options granted 210 ​ $ 9.00 ​ ​ ​ ​ ​ ​ Options canceled (489) ​ $ 4.77 ​ ​ ​ ​ ​ ​ Options exercised (4,818) ​ $ 3.23 ​ ​ ​ ​ ​ ​ Balances at December 31, 2020 11,191 ​ $ 3.75 6.51 ​ $ 58,842 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Options exercisable at December 31, 2020 8,897 ​ $ 3.35 6.28 ​ $ 50,343 ​ ​ The Company has computed the aggregate intrinsic value amounts disclosed in the above table based on the difference between the original exercise price of the options and the fair value of the Company’s common stock of $9.01 per share at December 31, 2020. The total intrinsic value of awards exercised during the years ended December 31, 2020, 2019, and 2018 was $23,991, $7,806, and $10,957, respectively. ​ Stock-Based Compensation ​ The Company recognizes stock-based compensation expense in accordance with ASC 718, and has estimated the fair value of each option award on the grant date using the Black-Scholes option valuation model and the weighted average assumptions noted in the following tables. ​ ​ ​ ​ ​ ​ ​ ​ Performance Stock Options ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ 2020 2019 2018 Dividend yield — % — % — % Risk-free interest rate — % — % 2.89 % Expected volatility — % — % 60.2 % Expected term (years) — ​ — ​ 5.98 ​ ​ ​ ​ ​ ​ ​ ​ Stock Options ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ 2020 2019 2018 Dividend yield — % — % — % Risk-free interest rate 0.28 % 1.88 % 2.63 % Expected volatility 69.3 % 57.2 % 57.9 % Expected term (years) 4.00 ​ 4.00 ​ 4.00 ​ ​ The expected term of stock options gave consideration to early exercises, post-vesting cancellations and the options’ contractual term ranging from 6 to 10 years. The Company does not have sufficient historical exercise data to provide a reasonable basis upon which to estimate the expected term for the PSOs as the Company has not granted such awards in the past. As a result, the Company used the simplified method to calculate the expected term estimate based on the vesting and contractual terms of the PSOs. Under the simplified method, the expected term is equal to the average of the stock-based awards vesting period and their contractual term. The PSOs have a contractual term of 10 years. The risk-free interest rate for the expected term of the option is based on the U.S. Treasury Constant Maturity Rate as of the date of grant. The Company based its expected volatility on its own historical volatility for the year ended December 31, 2020, 2019, and 2018, respectively. The weighted-average fair value of stock options granted during the year ended December 31, 2020, 2019, and 2018 was $4.63, $3.44, and $2.25 per share, respectively. The Company did not grant any PSOs in the year ended December 31, 2020 and 2019, respectively. The weighted average fair value of the PSOs granted during the year ended December 31, 2018 was $3.38. ​ The cost of RSUs and PSUs are determined using the fair value of the Company’s common stock based on the quoted closing price of the Company’s common stock on the date of grant. RSUs typically vest and are settled over approximately a four-year period with 25% of the shares vesting on or around the one-year anniversary of the grant date and the remaining shares vesting quarterly thereafter. Compensation cost for RSUs is amortized on a straight-line basis over the requisite service period. Compensation cost for PSUs is amortized on an accelerated attribution basis over the requisite service period of the award. The following table summarizes the consolidated stock-based compensation expense by line items in the consolidated statement of operations: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ ​ 2020 2019 2018 Research and development ​ $ 19,942 ​ $ 10,466 ​ $ 12,807 ​ Sales and marketing ​ 3,904 ​ 1,700 ​ 2,795 ​ General and administrative ​ 7,963 ​ 5,217 ​ 8,990 ​ Total stock-based compensation expense ​ $ 31,809 ​ $ 17,383 ​ $ 24,592 ​ ​ (1) For the year ended December 31, 2020, stock-based compensation expense recorded in research and development includes $739 from PSUs classified as liabilities. (2) Stock-based compensation expense for the year ended December 31, 2019 included a reversal of previously accrued expense of $2,455 due to a decrease in the vesting probability of certain performance-based equity awards. The following table summarizes total compensation expense related to unvested awards not yet recognized as of December 31, 2020: ​ ​ ​ ​ ​ ​ ​ Unrecognized Compensation ​ ​ Expense for Unvested ​ ​ Awards Stock options ​ $ 5,050 RSUs ​ ​ 36,789 PSUs ​ ​ 3,677 PSOs ​ ​ 325 Total unrecognized compensation expense ​ $ 45,841 (1) The unrecognized compensation expense for PSUs vesting in FY2023 and FY2024 is not included in the table above as the Company does not have a reasonable basis upon which to estimate the vesting probability of such awards in those future periods. ​ The unrecognized compensation expense related to stock options and RSUs will be recognized over a weighted average period of 1.26 years and 3.20 years, respectively. The unrecognized stock compensation expense related to unvested PSUs and PSOs will be recognized over a weighted average period of 0.52 and 0.13 years, respectively. ​ Stock-based compensation expense in the year ended December 31, 2020, was approximately $31,809 (comprising approximately $6,068 related to stock options, $12,732 related to performance-based awards, $11,177 related to RSUs and $1,832 related to the 2007 Purchase Plan). ​ Stock-based compensation expense in the year ended December 31, 2019, was approximately $17,383 (comprising approximately $7,043 related to stock options, $2,421 related to performance-based awards, $6,559 related to RSUs and $1,360 related to the 2007 Purchase Plan). ​ Stock-based compensation expense in the year ended December 31, 2018, was approximately $24,592 (comprising approximately $6,386 related to stock options, $9,195 related to performance-based awards, $8,084 related to RSUs and $927 related to the 2007 Purchase Plan). ​ Cash proceeds, net of taxes, from option exercises were $19,463, $3,305, and $5,643 for the years ended December 31, 2020, 2019, and 2018, respectively. The Company realized no significant income tax benefit from stock option exercises during the year ended December 31, 2020, 2019, and 2018. As permitted by ASC 718, the Company has deferred the recognition of its excess tax benefit from non-qualified stock option exercises. ​ 401(k) Defined Contribution Plan ​ The Company sponsors a 401(k) defined contribution plan covering certain eligible employees. In 2019, the Company started matching a portion of the contribution made by participants who met certain employment criteria. For the years ended December 31, 2020 and 2019, t he matching contributions made by the Company were not material. The Company did not match the contributions made by its employees for the year ended December 31, 2018.

INCOME TAXES

INCOME TAXES	12 Months Ended
	Dec. 31, 2020
INCOME TAXES
INCOME TAXES	NOTE 11 — INCOME TAXES ​ The components of income (loss) before income taxes by tax jurisdiction were as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ ​ 2020 2019 2018 United States ​ $ 19,279 ​ $ 7,047 ​ $ (12,396) ​ Foreign ​ ​ 2,307 ​ ​ 2,295 ​ ​ (254) ​ Income (loss) before income taxes ​ $ 21,586 ​ $ 9,342 ​ $ (12,650) ​ ​ The components of income tax benefit/(provision) were as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, Current: 2020 2019 2018 Federal ​ $ (122) ​ $ 373 ​ $ (96) State ​ ​ (161) ​ ​ (10) ​ ​ (8) Foreign ​ ​ (1,105) ​ ​ (590) ​ ​ (500) ​ ​ ​ (1,388) ​ ​ (227) ​ ​ (604) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Deferred: ​ ​ ​ ​ ​ ​ ​ ​ ​ Federal ​ ​ — ​ ​ — ​ ​ — Foreign ​ ​ 249 ​ ​ (244) ​ ​ 55 ​ ​ ​ 249 ​ ​ (244) ​ ​ 55 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total: ​ ​ ​ ​ ​ ​ ​ ​ ​ Federal ​ ​ (122) ​ ​ 373 ​ ​ (96) State ​ ​ (161) ​ ​ (10) ​ ​ (8) Foreign ​ ​ (856) ​ ​ (834) ​ ​ (445) ​ ​ $ (1,139) ​ $ (471) ​ $ (549) ​ The difference between the actual rate and the federal statutory rate was as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ ​ ​ 2020 ​ 2019 ​ 2018 Tax at federal statutory rate ​ ​ 21.0 % ​ 21.0 % ​ 21.0 % Meals and entertainment ​ ​ 0.3 ​ ​ 3.1 ​ ​ (2.0) ​ Research and development credit ​ ​ (24.4) ​ ​ (41.0) ​ ​ 21.3 ​ Stock-based compensation ​ ​ (24.4) ​ ​ (29.0) ​ ​ 17.9 ​ Revenue from contracts with customers ​ ​ — ​ ​ — ​ ​ (14.6) ​ Others ​ ​ 3.1 ​ ​ (0.6) ​ ​ (3.1) ​ Global intangible low-taxed income ​ ​ 0.8 ​ ​ 4.2 ​ ​ (1.7) ​ Valuation allowance ​ ​ 10.2 ​ ​ 17.5 ​ ​ (35.3) ​ Executive compensation ​ ​ 8.6 ​ ​ 6.1 ​ ​ — ​ Foreign tax credit ​ ​ 8.2 ​ ​ 23.7 ​ ​ (7.8) ​ Other non-deductible expenses ​ ​ 1.9 ​ ​ — ​ ​ — ​ Effective tax rate ​ ​ 5.3 % ​ 5.0 % ​ (4.3) % ​ Deferred tax assets and liabilities consist of the following: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2020 ​ December 31, 2019 ​ US Foreign Total US Foreign Total Deferred tax assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fixed assets ​ $ 654 ​ $ 71 ​ $ 725 ​ $ 209 ​ $ 71 ​ $ 280 Net operating loss carryforwards ​ ​ 42,822 ​ ​ 7 ​ ​ 42,829 ​ ​ 48,968 ​ ​ 25 ​ ​ 48,993 Accruals, reserves and other ​ ​ 7,460 ​ ​ 401 ​ ​ 7,861 ​ ​ 3,939 ​ ​ 121 ​ ​ 4,060 Foreign tax credit ​ ​ 1,138 ​ ​ — ​ ​ 1,138 ​ ​ 2,905 ​ ​ — ​ ​ 2,905 Stock-based compensation ​ ​ 5,494 ​ ​ — ​ ​ 5,494 ​ ​ 5,882 ​ ​ — ​ ​ 5,882 Research and development credit ​ ​ 27,899 ​ ​ — ​ ​ 27,899 ​ ​ 22,630 ​ ​ — ​ ​ 22,630 Capitalized research and development ​ ​ 7,784 ​ ​ — ​ ​ 7,784 ​ ​ 7,189 ​ ​ — ​ ​ 7,189 Intangible assets ​ ​ 988 ​ ​ — ​ ​ 988 ​ ​ 355 ​ ​ — ​ ​ 355 Operating lease liabilities ​ ​ 8,708 ​ ​ 155 ​ ​ 8,863 ​ ​ 8,926 ​ ​ 117 ​ ​ 9,043 Other ​ ​ 2,773 ​ ​ — ​ ​ 2,773 ​ ​ 2,951 ​ ​ — ​ ​ 2,951 Total deferred tax assets ​ $ 105,720 ​ $ 634 ​ $ 106,354 ​ $ 103,954 ​ $ 334 ​ $ 104,288 Deferred tax liabilities: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fixed assets ​ $ — ​ $ (68) ​ $ (68) ​ $ — ​ $ (40) ​ $ (40) Operating lease right of use assets ​ ​ (6,961) ​ ​ (144) ​ ​ (7,105) ​ ​ (7,663) ​ ​ (104) ​ ​ (7,767) Net deferred tax assets ​ ​ 98,759 ​ ​ 422 ​ ​ 99,181 ​ ​ 96,291 ​ ​ 190 ​ ​ 96,481 Less valuation allowance ​ ​ (98,759) ​ ​ (7) ​ ​ (98,766) ​ ​ (96,291) ​ ​ (25) ​ ​ (96,316) Net deferred tax assets ​ $ — ​ $ 415 ​ $ 415 ​ $ — ​ $ 165 ​ $ 165 ​ The Company has not provided deferred taxes on unremitted earnings attributable to foreign subsidiaries, because their earnings are intended to be reinvested indefinitely. The amount of accumulated foreign earnings of the Company’s foreign subsidiaries totaled $3,734 as of December 31, 2020. If the Company's foreign earnings were repatriated, additional tax expense might result. The Company determined that the calculation of the amount of unrecognized deferred tax liability related to these cumulative unremitted earnings attributable to foreign subsidiaries is not practicable. ​ After considering all available positive and negative evidence, the Company has determined it is more likely than not that deferred tax assets in the U.S. and a certain foreign entity will not be realized as a result of cumulative losses incurred in these jurisdictions, except for Canada and India. Therefore, the Company maintains a full valuation allowance against the net deferred tax assets in these jurisdictions. As of December 31, 2020 and 2019, the Company concluded that an additional valuation allowance of $2,450 and $2,334 was required to reflect the change in its deferred tax assets prior to valuation allowance during 2020 and 2019, respectively. It is reasonably possible that within the next 12 months, there may be sufficient positive evidence to release a portion or all of the valuation allowance. Release of the valuation allowance would result in a benefit to income tax expense for the period the release is recorded, which could have a material impact on net earnings. The timing and amount of the potential valuation allowance release are subject to significant management judgment and prospective earnings. ​ At December 31, 2020, the Company had net operating loss carryforwards of approximately $182,400 and $90,547 for federal and state tax purposes, respectively. If not utilized, these carryforwards will expire at various times between 2026 and 2040. In addition, the Company has research and development tax credit carryforwards of approximately of foreign tax credits that will begin to expire in 2021. The Company’s ability to use its net operating loss carryforwards and federal and state tax credit carryforwards to offset future taxable income and future taxes, respectively, may be subject to restrictions attributable to equity transactions that result in changes in ownership as defined by Internal Revenue Code Section 382. ​ A reconciliation of the total amounts of unrecognized tax benefits was as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ 2020 2019 Beginning balance ​ $ 15,084 ​ $ 20,718 Reductions of tax positions taken during previous years ​ ​ — ​ ​ (8,226) Additions based on uncertain tax positions related to the current period ​ ​ 3,940 ​ ​ 2,598 Additions based on uncertain tax positions related to prior periods ​ ​ 61 ​ ​ — Cumulative translation adjustment ​ ​ — ​ ​ (6) Ending balance ​ $ 19,085 ​ $ 15,084 ​ The total unrecognized tax benefits as of December 31, 2020 and 2019 included approximately $19,035 and $15,084, respectively, of unrecognized tax benefits that have been netted against deferred tax assets. As of December 31, 2020, the Company does not expect the unrecognized tax benefits, if recognized, to have a material impact on its financial statements. ​ The Company’s policy is to recognize interest and penalties related to unrecognized tax benefits in income tax expense. The current and accumulated accrual of interest and penalties on uncertain tax positions is immaterial. ​ The Company is subject to taxation in the United States and various foreign jurisdictions. The material jurisdictions subject to examination by tax authorities are primarily the State of California, the United States, Canada and India. The Company’s federal tax returns are open by statute for tax years 1998 and California tax returns are open by statute for tax years 2003 and forward and could be subject to examination by the tax authorities. ​ On March 27, 2020, the President of the United States signed and enacted into law the Coronavirus Aid, Relief and Economic Security ("CARES") Act, which contains several income tax provisions, as well as other measures, aimed at assisting businesses impacted by the economic effects of the COVID-19 pandemic. Among other provisions, the CARES Act removes certain limitations on utilization of net operating losses ("NOLs") and allows for carrybacks of certain past and future NOLs. The Company does not anticipate the income tax provisions of the CARES Act to have a material impact on its financial statements.

SEGMENT INFORMATION AND OPERATI

SEGMENT INFORMATION AND OPERATIONS BY GEOGRAPHIC AREA	12 Months Ended
	Dec. 31, 2020
SEGMENT INFORMATION AND OPERATIONS BY GEOGRAPHIC AREA
SEGMENT INFORMATION AND OPERATIONS BY GEOGRAPHIC AREA	NOTE 12 — SEGMENT INFORMATION AND OPERATIONS BY GEOGRAPHIC AREA ​ Operating segments are defined as components of an enterprise for which separate financial information is available that is evaluated regularly by the chief operating decision-maker (“CODM”), or decision making group, whose function is to allocate resources to and assess the performance of the operating segments. The Company has identified its Chief Executive Officer as the CODM. The Company operates in a single operating segment. The financial information reviewed by the CODM is included within one operating segment for purposes of allocating resources and evaluating financial performance ​ The following tables set forth revenue and long-lived assets based on geography: ​ Revenue ​ Revenue by geography is primarily based on the geographic location of the Company’s payers. International revenue is revenue generated from distributors and advertising service providers whose principal operations are located outside the United States or, in the case of the Digital Storefronts, the revenue generated from end-user purchases made outside of the United States. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ ​ 2020 2019 2018 United States of America ​ $ 424,865 ​ $ 320,343 ​ $ 280,264 ​ Americas, excluding the United States ​ 32,003 ​ 25,240 ​ 21,903 ​ EMEA ​ 57,353 ​ 45,700 ​ 41,585 ​ APAC ​ 26,301 ​ 20,098 ​ 22,809 ​ Total revenue ​ $ 540,522 ​ $ 411,381 ​ $ 366,561 ​ ​ Long-Lived Assets ​ The Company attributes its long-lived assets, which primarily consist of property and equipment, to a country primarily based on the physical location of the assets. Property and equipment, net of accumulated depreciation and amortization, summarized by geographic location was as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ 2020 2019 United States of America ​ $ 14,868 ​ $ 16,738 ​ Rest of the World ​ 786 ​ 905 ​ Total ​ $ 15,654 ​ $ 17,643 ​ ​

SUBSEQUENT EVENTS

SUBSEQUENT EVENTS	12 Months Ended
	Dec. 31, 2020
SUBSEQUENT EVENTS.
SUBSEQUENT EVENTS	NOTE 13 — SUBSEQUENT EVENTS ​ ​

QUARTERLY FINANCIAL DATA (unaud

QUARTERLY FINANCIAL DATA (unaudited)	12 Months Ended
	Dec. 31, 2020
QUARTERLY FINANCIAL DATA (unaudited)
QUARTERLY FINANCIAL DATA (unaudited)	NOTE 14 – QUARTERLY FINANCIAL DATA (unaudited) ​ The following table sets forth unaudited quarterly consolidated statements of operations data for 2020 and 2019. The Company derived this information from its unaudited condensed consolidated financial statements, which it prepared on the same basis as its audited consolidated financial statements contained in this report. These unaudited statements include all adjustments, consisting only of normal recurring adjustments that the Company considers necessary for a fair statement of that information for the periods presented. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the Three Months Ended ​ ​ 2020 ​ 2019 ​ March 31, June 30, September 30, December 31, March 31, June 30, September 30, December 31, ​ ​ ​ ​ Revenue ​ $ 107,274 ​ $ 133,316 ​ $ 158,531 ​ $ 141,401 ​ $ 95,885 ​ $ 95,540 ​ $ 107,077 ​ $ 112,879 Cost of revenue: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Platform commissions, royalties and other ​ ​ 36,974 ​ ​ 46,727 ​ ​ 56,390 ​ ​ 48,204 ​ ​ 33,270 ​ ​ 32,806 ​ ​ 36,758 ​ ​ 38,278 Impairment and amortization of intangible assets ​ ​ 888 ​ ​ 887 ​ ​ 888 ​ ​ 595 ​ ​ 1,252 ​ ​ 1,056 ​ ​ 1,040 ​ ​ 1,039 Total cost of revenue ​ ​ 37,862 ​ ​ 47,614 ​ ​ 57,278 ​ ​ 48,799 ​ ​ 34,522 ​ ​ 33,862 ​ ​ 37,798 ​ ​ 39,317 Gross profit ​ ​ 69,412 ​ ​ 85,702 ​ ​ 101,253 ​ ​ 92,602 ​ ​ 61,363 ​ ​ 61,678 ​ ​ 69,279 ​ ​ 73,562 Operating expenses: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Research and development ​ ​ 29,531 ​ ​ 28,420 ​ ​ 30,778 ​ ​ 30,989 ​ ​ 26,546 ​ ​ 19,736 ​ ​ 22,968 ​ ​ 25,877 Sales and marketing ​ ​ 42,743 ​ ​ 65,203 ​ ​ 42,222 ​ ​ 27,077 ​ ​ 28,105 ​ ​ 35,040 ​ ​ 46,140 ​ ​ 31,013 General and administrative ​ ​ 6,667 ​ ​ 7,266 ​ ​ 7,870 ​ ​ 9,688 ​ ​ 6,635 ​ ​ 4,951 ​ ​ 5,879 ​ ​ 5,751 Total operating expenses ​ ​ 78,941 ​ ​ 100,889 ​ ​ 80,870 ​ ​ 67,754 ​ ​ 61,286 ​ ​ 59,727 ​ ​ 74,987 ​ ​ 62,641 Income/(loss) from operations ​ ​ (9,529) ​ ​ (15,187) ​ ​ 20,383 ​ ​ 24,848 ​ ​ 77 ​ ​ 1,951 ​ ​ (5,708) ​ ​ 10,921 Interest and other income/(expense), net ​ ​ (65) ​ ​ 434 ​ ​ 413 ​ ​ 289 ​ ​ 764 ​ ​ 556 ​ ​ 271 ​ ​ 510 Income/(loss) before income taxes ​ ​ (9,594) ​ ​ (14,753) ​ ​ 20,796 ​ ​ 25,137 ​ ​ 841 ​ ​ 2,507 ​ ​ (5,437) ​ ​ 11,431 Income tax (provision)/benefit ​ ​ 1,321 ​ ​ 6,187 ​ ​ (7,391) ​ ​ (1,256) ​ ​ (178) ​ ​ — ​ ​ 348 ​ ​ (641) Net income/(loss) ​ $ (8,273) ​ $ (8,566) ​ $ 13,405 ​ $ 23,881 ​ $ 663 ​ $ 2,507 ​ $ (5,089) ​ $ 10,790 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income/(loss) per share ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Basic ​ $ (0.06) ​ $ (0.05) ​ $ 0.08 ​ $ 0.14 ​ $ 0.00 ​ $ 0.02 ​ $ (0.03) ​ $ 0.07 Diluted ​ $ (0.06) ​ $ (0.05) ​ $ 0.07 ​ $ 0.13 ​ $ 0.00 ​ $ 0.02 ​ $ (0.03) ​ $ 0.07 ​

THE COMPANY AND SUMMARY OF SI_2

THE COMPANY AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	12 Months Ended
	Dec. 31, 2020
THE COMPANY AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
Basis of Presentation	Basis of Presentation ​ The Company's consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States (“U.S. GAAP”).
Principles of Consolidation	Principles of Consolidation ​ The consolidated financial statements include the accounts of the Company and its wholly owned subsidiaries. All intercompany balances and transactions have been eliminated on consolidation.
Use of Estimates	Use of Estimates ​ The preparation of financial statements in conformity with U.S. GAAP requires the Company’s management to make judgments, assumptions and estimates that affect the amounts reported in its consolidated financial statements and accompanying notes. Management bases its estimates on historical experience and on various other assumptions it believes to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities. Estimates and assumptions reflected in the consolidated financial statements include, but are not limited to, estimation of the average playing period of paying users associated with durable virtual items, the allowance for doubtful accounts, useful lives of property and equipment and intangible assets, valuation and realizability of deferred tax assets and uncertain tax positions, fair value of stock awards issued, fair value of warrants issued, accounting for business combinations, evaluating goodwill, long-lived assets for impairment, and realization of prepaid royalties and fair value of investments. Actual results may differ from these estimates due to risks and uncertainties, and these differences may be material, including uncertainty in the current economic environment due to the novel strain of coronavirus, SARS-CoV-2 (“COVID-19”) pandemic. Management will continue to actively monitor the impact of the COVID-19 pandemic on the Company’s assumptions and estimates.
Revenue Recognition	Revenue Recognition ​ The Company generates revenue through in-application purchases (“in-app purchases”) within its games on smartphones and tablet devices, such as Apple’s iPhone and iPad, and mobile devices utilizing Google’s Android operating system. Users can download the Company’s free-to-play games ​ The Company adopted Accounting Standard Codification Topic 606, Revenue from Contracts with Customers, (“ASC 606”) and identifies the payment terms related to these services, (ii) the contract has commercial substance and, (iii) the Company determines that collection of substantially all consideration for services that are transferred is probable based on the customer’s intent and ability to pay the promised consideration. The Company applies judgment in determining the customer’s ability and intention to pay, which is based on a variety of factors including the customer’s historical payment experience or, in the case of a new customer, published credit and financial information pertaining to the customer. ​ ASC 606 requires an entity to disclose the revenue recognized in the reporting period from performance obligations satisfied (or partially satisfied) in previous periods (for example, due to changes in transaction price). Revenue recognized relating to performance obligations satisfied in prior periods was $0 for the year ended December 31, 2020 and December 31, 2019, respectively. The Company elects to use the practical expedient under 606-10-50-14 which states an entity need not disclose the information in paragraph 606-10-50-13 for a performance obligation if the following criteria are met: ​ 1. the performance obligation is part of a contract that has an original expected duration of one year or less; and 2. the entity recognizes revenue from the satisfaction of the performance obligation in accordance with paragraph 606-10-55-18 (right to invoice). ​ Since all of the Company’s contracts have an original expected duration of one year or less, the Company elects to use this practical expedient and does not disclose the aggregate transaction price allocated to unsatisfied or partially satisfied performance obligations. ​ In-App Purchases Users can download the Company’s free-to-play games within the Digital Storefronts and pay to acquire virtual currency, which can be redeemed in the game for virtual goods, or virtual goods directly (together, defined as “virtual items”) to enhance their game-playing experience. The Company sells both consumable and durable virtual items and receives reports from the Digital Storefronts, which breakdown the various purchases made from the Company’s games over a given time period. The Company reviews these reports and determines on a per-item basis whether the purchase was a consumable virtual item or a durable virtual item. Consumable virtual items are items that are consumed at a predetermined time or otherwise have limitations on repeated use. Durable virtual items are items, such as furniture, clothes, etc. that are accessible to the player over an extended period of time and that remain in the game for as long as the player continues to play. ​ The initial download of the mobile game from the Digital Storefront does not create a contract under ASC 606 because of the lack of commercial substance; however, the separate election by the player to make an in-application purchase satisfies the criterion thus creating a contract under ASC 606. The Company has identified the following performance obligations in these contracts: 1. Ongoing game related services such as hosting of game play, storage of customer content, when and if available content updates, maintaining the virtual currency management engine, tracking gameplay statistics, matchmaking as it relates to multiple player gameplay, etc. 2. Obligation to the paying player to continue displaying and providing access to the virtual items within the game. ​ Neither of these obligations are considered distinct since the actual mobile game and the related ongoing services are both required to purchase and benefit from the related virtual items. As such, the Company’s performance obligations represent a single combined performance obligation which is to make the game and the ongoing game related services available to the players. The transaction price, which is the amount paid for the virtual items by the player, is allocated entirely to the single combined performance obligation. The Company recognizes revenue for durable virtual items over the estimated average playing period of paying users on a per title basis. The Company’s revenue from consumable virtual items has been insignificant over the previous three years. The Company has estimated the useful life of a paying user between four ​ Advertisements and Offers The Company has relationships with certain advertising service providers for advertisements within its mobile games. Revenue from these advertising service providers is generated through impressions, clickthroughs, offers and banner ads. Offers are the type of advertisements where the players are rewarded with virtual currency for completing specified actions, such as downloading another application, watching a short video, subscribing to a service or completing a survey. The Company has determined the advertising buyer to be its customer and displaying the advertisements within the mobile games is identified as the single performance obligation. Revenue from advertisements and offers are recognized at the point-in-time the advertisements are displayed in the game or the offer has been completed by the user as the customer simultaneously receives and consumes the benefits provided from these services. ​ Other Estimates and Judgments The Company computes its estimated average playing period of paying users at least twice each year. It has examined the playing patterns of paying users across a representative sample of its games across various genres. The Company uses the “survival analysis” model to estimate the average playing period for paying users. This model provides for a singular approach to estimating the average playing period of paying users on a title by title basis for the Company’s diverse portfolio of games. It is a statistical model that analyzes time duration until one or more events happens and is commonly used in various industries for estimating lifespans. The Company believes this is an appropriate model to estimate the average playing period of paying users for its titles as this model statistically estimates the average playing period of each title by analyzing the historical behavior patterns of paying users. ​ This model requires the stratification of user data into active and inactive paying users on a per title basis. Active users are those who are active in the game for the past 30 days as of the evaluation date. The remaining users are considered inactive and deemed to have churned from the game. These users are treated mathematically differently in the model than those who are still active. A distribution curve is then fit to the user data to estimate the average playing period of paying users on a per title basis. ​ The Company has selected a threshold of 120 days from the commercial launch of a title as the minimum number of days of data required for this model. This threshold was deemed to be appropriate as the Company tested the model using lower thresholds which resulted in inconsistencies in the estimate of the average playing period of paying users. For new titles with less than 120 days of data that share similar attributes with an existing title and/or prequel titles, the average playing period is determined based on the average playing period of that existing title or prequel title, as applicable. For all other titles with less than 120 days of data, the average playing period is determined based on the average playing period of all other remaining existing titles. ​ While the Company believes its estimates to be reasonable based on available game player information, it may revise such estimates in the future if a titles’ user characteristics change. Any adjustments arising from changes in the estimates of the average playing period for paying users would be applied to the current quarter and prospectively on the basis that such changes are caused by new information that indicates a change in user behavior patterns compared to historical titles. Any changes in the Company’s estimates of the useful life of virtual items in a certain title may result in revenue being recognized on a basis different from prior periods’ and may cause its operating results to fluctuate. ​ Principal Agent Considerations ​ The Company evaluated its Digital Storefront and advertising service provider agreements under ASC 606 in order to determine if it is acting as the principal or as an agent when selling virtual items or advertisements within its games. The Company primarily uses Digital Storefronts for distributing its smartphone games and for enabling players to purchase virtual items and advertising service providers to serve advertisements within its games. The Company evaluated the following factors to assess whether it controls each specified good or service before that good or service is transferred to the customer: ​ ● the party responsible for the fulfillment of the virtual items, game related services, or serving of advertisements; ● the party having the discretion to set pricing with the end-users; and ● the party having inventory risk before the specified good or service have been transferred to a customer. ​ Based on the evaluation of the above indicators, the Company determined that it has control of the services before they are transferred to the end-user. Thus, the Company is generally acting as a principal and is the primary obligor to end-users for games distributed through Digital Storefronts and advertisements served through its advertising service providers. Therefore, the Company recognizes revenue related to these arrangements on a gross basis, when the necessary information about the gross amounts or platform fees charged, before any adjustments, are made available by the Digital Storefronts and advertising service providers. In situations where the price paid by the end-user of the advertising service provider is not known, the Company accounts for these transactions on a net basis. ​ Deferred Platform Commissions and Royalties ​ Digital Storefronts retain platform commissions and fees on each purchase made by the paying players through the Digital Storefront. The Company is also obligated to pay ongoing licensing fees in the form of royalties related to the games developed based on or significantly incorporating licensed brands, properties or other content, and the Company plans to incorporate additional licensed content in some of its own originally branded games. As revenue from sales to paying players through Digital Storefronts are deferred, the related direct and incremental platform commissions and fees as well as third-party royalties are also deferred on the consolidated balance sheets. The deferred platform commissions and royalties are recognized in the consolidated statements of operations in “Cost of revenue” in the period in which the related sales are recognized as revenue.
Cash and Cash Equivalents	Cash and Cash Equivalents ​ Cash and cash equivalents consist of cash on hand and money market funds. The Company considers all investments purchased with original maturities of three months or less from the date of purchase to be cash equivalents. The Company deposits cash and cash equivalents with financial institutions that management believes are of high credit quality. Deposits held with financial institutions often exceed the amount of insurance on these deposits.
Concentration of Credit Risk	Concentration of Credit Risk ​ Financial instruments that potentially subject the Company to a concentration of credit risk consist of cash, cash equivalents and accounts receivable. ​ ​ The following table summarizes the revenue from customers or aggregate purchases through Digital Storefronts in excess of 10% of the Company’s revenue: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ ​ 2020 2019 2018 Apple ​ 56.2 % 54.4 % 54.7 % Google ​ 32.9 % 33.5 % 31.3 % ​ At December 31, 2020, Apple Inc. (“Apple”), Google Inc. (“Google”), and Tapjoy Inc. (“Tapjoy”) accounted for 42.7%, 28.8%, and 22.0%, respectively, of total accounts receivable. At December 31, 2019, Apple, Google and Tapjoy accounted for 47.2%, 28.5%, and 17.8%, respectively, of total accounts receivable. No other customer represented more than 10% of the Company’s total accounts receivable as of these dates.
Fair Value	Fair Value ​ Accounting Standard Codification 820 Fair Value Measurements and Disclosures ​ Level 1 ​ Level 2 ​ Level 3
Foreign Currencies	Foreign Currencies ​ ​ Cumulative foreign currency translation adjustments include any gain or loss associated with the translation of a subsidiary’s financial statements when the functional currency of a subsidiary is the local currency. If the Company disposes of any of its subsidiaries, any cumulative translation gains or losses would be realized and recorded in other income (expense) within the Company’s consolidated statement of operations in the period during which the disposal occurs. If the Company determines that there has been a change in the functional currency of a subsidiary from a local currency to the U.S. Dollar, any translation gains or losses arising after the date of change would be included in interest and other income/(expense), net within the Company’s consolidated statement of operations.
Prepaid or Guaranteed Licensor Royalties	Prepaid or Guaranteed Licensor Royalties ​ The Company’s royalty expenses consist of fees that it pays to content owners for the use of their brands, properties and other licensed content, including trademarks and copyrights, in the development of the Company’s games. Royalty-based obligations are either paid in advance and capitalized on the balance sheet as prepaid royalties or accrued as incurred and subsequently paid. These royalty-based obligations are expensed to cost of revenue at the greater of the revenue derived from the relevant game multiplied by the applicable contractual rate or an effective royalty rate based on expected net product sales. ​ The Company’s contracts with some licensors include minimum guaranteed royalty payments, which are payable regardless of the ultimate revenue generated from end users. In accordance with Accounting Standard Codification 440-10 Commitments accrued royalties on the Company’s consolidated balance sheet. When no significant performance remains with the licensor, the Company initially records each of these guarantees as an asset and as a liability at the contractual amount. When significant performance remains with the licensor, the Company records royalty payments as an asset when actually paid and as a liability when incurred, rather than upon execution of the contract. The classification of minimum royalty payment obligations between long-term and short-term is determined based on the expected timing of recoupment of earned royalties calculated on projected revenue for the licensed IP games. ​ Each quarter, the Company evaluates the realization of its prepaid royalties as well as any recognized guarantees not yet paid to determine amounts that it deems unlikely to be realized through product sales. The Company uses estimates of revenue, cash flows and net margins to evaluate the future realization of prepaid royalties, license fees, and guarantees. This evaluation considers multiple factors such as the term of the agreement, forecasted demand, game life cycle status, game development plans, and current and anticipated sales levels, as well as other qualitative factors such as the success of similar games and similar genres on mobile devices published by the Company and its competitors other game platforms (e.g., consoles and personal computers) utilizing the intellectual property. To the extent that this evaluation indicates that the remaining prepaid and guaranteed royalty payments are not recoverable, the Company records an impairment charge to cost of revenue in the period in which impairment is indicated. related to prepaid guaranteed royalties for certain of its celebrity license agreements, and certain other prepaid royalties
Goodwill and Intangible Assets	Goodwill and Intangible Assets ​ In accordance with Accounting Standard Codification 350 Intangibles-Goodwill and Other th ​ Qualitative assessment ​ Quantitative assessment ​ When necessary, to determine the reporting unit’s fair value under the quantitative approach, the Company uses a combination of income and market approaches, such as estimated discounted future cash flows of that reporting unit, multiples of earnings or revenue, and an analysis of recent sales or offerings of comparable entities. The Company also considers its market capitalization on the date of the analysis to ensure the reasonableness of the reporting unit’s fair value. ​ In 2020, 2019, and 2018, the Company did not ​ Purchased intangible assets with finite lives are amortized using the straight-line method over their useful lives ranging from three 360, Property, Plant and Equipment
Impairment of Long-Lived Assets	​ Impairment of Long-Lived Assets ​ The Company evaluates its long-lived assets, including property and equipment and intangible assets with finite lives, for impairment whenever events or changes in circumstances indicate that the carrying value of these assets may not be recoverable. Factors considered important that could result in an impairment review include significant underperformance relative to expected historical or projected future operating results, significant changes in the manner of use of acquired assets, significant negative industry or economic trends, and a significant decline in the Company’s stock price for a sustained period of time. Impairment exists if the carrying amounts of such assets exceed the estimates of future undiscounted cash flows expected to be generated by such assets. Should an impairment exist, the impairment loss would be measured based on the excess carrying value of the asset over expected discounted future cash flows, or if applicable, the quoted market price from those assets. The Company has not recorded any such impairment charge during the years presented.
Property and Equipment	Property and Equipment ​ The Company states property and equipment at cost less accumulated depreciation and amortization. The Company computes depreciation or amortization using the straight-line method over the estimated useful lives of the respective assets or, in the case of leasehold improvements, the lease term of the respective assets, whichever is shorter. Cost of maintenance and repairs that do not improve or extend the lives of the respective assets are expensed as incurred. ​ The depreciation and amortization periods for the Company’s property and equipment are as follows: ​ ​ ​ ​ Computer equipment Three years ​ Computer software Two ​ Furniture and fixtures Three years ​ Leasehold improvements Shorter of the estimated useful life or remaining term of lease ​
Internal Use Software	Internal Use Software ​ The Company capitalizes internal use software development costs in accordance with Accounting Standard Codification 350-40 Intangibles-Goodwill and Other-Internal Use Software Accounting Standards Update 2015-05 Cloud Computing Arrangements ​
Research and Development Costs	Research and Development Costs ​ The Company charges costs related to research, design and development of products to research and development expense as incurred. The types of costs included in research and development expenses include personnel-related expenses such as salaries and benefits related to product development employees, third party development cost, contractor fees, and allocated facilities costs.
Software Development Costs	Software Development Costs ​ The Company applies the principles of Accounting Standard Codification 985-20 Software-Costs of Computer Software to Be Sold, Leased, or Otherwise Marketed
Stock-Based Compensation	Stock-Based Compensation ​ The Company applies the fair value provisions of Accounting Standard Codification 718 Compensation-Stock Compensation ​ The cost of RSUs and PSUs is determined using the fair value of the Company’s common stock based on the quoted closing price of the Company’s common stock on the date of grant. Compensation cost for stock options, RSUs and performance-based awards with a single vesting date is amortized ratably over the requisite service period. For performance-based awards that have multiple vesting dates, the compensation cost is recognized ratably over the requisite service period for each tranche, whereby each vesting tranche is treated as a separate award for determining the requisite service period. The compensation cost for performance-based awards may be adjusted over the vesting period based on interim estimates of performance against the pre-set financial performance measures.
Advertising Expenses	Advertising Expenses ​ The Company expenses the production costs of advertising, including direct response advertising, the first time the advertising takes place. Advertising expense was $146,207, $117,979, and $95,037 in the years ended December 31, 2020, 2019, and 2018, respectively.
Income Taxes	Income Taxes ​ The Company accounts for income taxes in accordance with Accounting Standard Codification 740 Income Taxes ​ The Company accounts for uncertain tax positions in accordance with ASC 740, which requires companies to adjust their financial statements to reflect only those tax positions that are more-likely-than-not to be sustained. ASC 740 prescribes a comprehensive model for the financial statement recognition, measurement, presentation and disclosure of uncertain tax positions taken or expected to be taken in income tax returns. The Company’s policy is to recognize interest and penalties related to unrecognized tax benefits in income tax expense. ​
Comprehensive Income/(Loss)	Comprehensive Income/(Loss) ​ Comprehensive income/(loss) consists of two components, net income/(loss) and other comprehensive income/(loss). Other comprehensive income/(loss) refers to revenue, expenses, gains and losses that under GAAP are recorded as an element of stockholders’ equity but are excluded from net income/(loss). The Company’s other comprehensive income/(loss) included foreign currency translation adjustments from those subsidiaries not using the U.S. Dollar as their functional currency, and a reclassification to net income/(loss) from the write-off of cumulative translation adjustment.
Operating Leases	Operating Leases ​ Effective January 1, 2019, the Company adopted Accounting Standards Update (“ASU”) No. 2016-02, Leases (Topic 842) and its related amendments. According to ASC 842, the Company determines if an arrangement is a lease at inception. Its operating lease agreements are primarily for real estate space and are included within operating lease right of use (“ROU”) assets and operating lease liabilities on the consolidated balance sheets. ​ ROU assets represent the Company’s right to use an underlying asset for the lease term and operating lease liabilities represent its obligation to make lease payments arising from the lease. ROU assets and operating lease liabilities are recognized at the commencement date based on the present value of lease payments over the lease term. As the Company’s leases do not provide an implicit rate, the Company uses its incremental borrowing rate, determined as the rate it would have incurred to borrow based on its credit quality at the inception of the lease over a similar term and in the economic environment where the leased asset is located, to calculate the present value of lease payments. ROU assets also exclude lease incentives. Many of the Company’s lease agreements include options to extend the lease, which the Company does not include in the minimum lease terms unless they are reasonably certain to be exercised. Rental expense for lease payments related to operating leases is recognized on a straight-line basis over the lease term. ​ Certain of the Company’s lease agreements contain lease components (for example, fixed payments such as rent) and non-lease components such as common-area maintenance costs. Both of these types of provisions are accounted for as a single lease component. For such arrangements, there may be a variability in future lease payments as the amount of the non-lease components is typically revised from one period to the next. These variable lease payments, which are primarily comprised of common-area maintenance, utilities, and real estate taxes that are passed on from the lessor in proportion to the space leased by the Company within the entire building or building complex, are recognized in the period in which the obligation for those payments is incurred ​ For leases that have greater than 12-month lease term, ROU assets and lease liabilities are recognized on the consolidated balance sheet at commencement date based on the present value of remaining fixed lease payments. The Company considers only payments that are fixed and determinable at the time of commencement . Short-term leases with an initial term of 12 months or less are not recorded on the balance sheet. The Company combines fixed lease and non-lease components and account for them as a single lease component.
Recent Accounting Pronouncements	Recent Accounting Pronouncements ​ Recently Adopted Accounting Pronouncements ​ In June 2016, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2016-13, “Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments” , which requires the measurement and recognition of expected credit losses for financial assets held at amortized cost and replaces the existing incurred loss impairment model with an expected loss methodology, which will result in earlier recognition of credit losses. The ASU requires a cumulative-effect adjustment to retained earnings transition approach and is effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. The adoption of this standard did not have a material impact on the Company’s consolidated financial statements. ​ In January 2017, the FASB issued ASU No. 2017-04, Intangibles—Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment . This new accounting standard update simplifies the measurement of goodwill by eliminating the Step 2 impairment test. Step 2 measures a goodwill impairment loss by comparing the implied fair value of a reporting unit’s goodwill with the carrying amount of that goodwill. The new guidance requires an entity to compare the fair value of a reporting unit with its carrying amount and recognize an impairment charge for the amount by which the carrying amount exceeds the reporting unit’s fair value, limited to the amount of goodwill. Additionally, an entity should consider income tax effects from any tax deductible goodwill on the carrying amount of the reporting unit when measuring the goodwill impairment loss, if applicable. The new guidance becomes effective for goodwill impairment tests in fiscal years beginning after December 15, 2019. The adoption of this standard did not have a material impact on the Company’s consolidated financial statements. ​ In August 2018, the FASB issued ASU 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework – Changes to the Disclosure Requirements for Fair Value Measurement. This guidance adds, modifies and removes several disclosure requirements relative to the three levels of inputs used to measure fair value in accordance with Topic 820, Fair Value Measurement. This guidance is effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. The adoption of this standard did not have a material impact on the Company’s consolidated financial statements. ​ In August 2018, the FASB issued ASU 2018-15, Intangibles – Goodwill and Other – Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract . This guidance aligns the requirements for capitalizing implementation costs incurred in a hosting arrangement that is a service contract with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software. This guidance is effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. The adoption of this standard did not have a material impact on the Company’s consolidated financial statements. ​ Recently Issued Accounting Pronouncements Not Yet Adopted In December 2019, the FASB issued ASU 2019-12, Income Taxes (Topic 740) : Simplifying the Accounting for Income Taxes . In October 2020, the FASB issued ASU 2020-10, Codification Improvements

THE COMPANY AND SUMMARY OF SI_3

THE COMPANY AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Tables)	12 Months Ended
	Dec. 31, 2020
THE COMPANY AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
Schedule of Revenue Concentration	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ ​ 2020 2019 2018 Apple ​ 56.2 % 54.4 % 54.7 % Google ​ 32.9 % 33.5 % 31.3 %
Schedule of Depreciation And Amortization Periods for Property and Equipment	​ ​ ​ ​ Computer equipment Three years ​ Computer software Two ​ Furniture and fixtures Three years ​ Leasehold improvements Shorter of the estimated useful life or remaining term of lease ​

NET INCOME_(LOSS) PER SHARE (Ta

NET INCOME/(LOSS) PER SHARE (Tables)	12 Months Ended
	Dec. 31, 2020
NET INCOME/(LOSS) PER SHARE
Computation of Net Income/(Loss) Per Share	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ 2020 2019 2018 Net income/(loss) ​ $ 20,447 ​ $ 8,871 ​ $ (13,199) ​ Shares used to compute net income/(loss) per share: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted average shares used to compute basic net income/(loss) per share ​ ​ 162,521 ​ ​ 145,838 ​ ​ 141,402 ​ Dilutive potential common shares ​ ​ 10,646 ​ ​ 11,545 ​ ​ — ​ Weighted average shares used to compute diluted net income/(loss) per share ​ 173,167 ​ 157,383 ​ 141,402 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Basic net income/(loss) per share ​ $ 0.13 ​ $ 0.06 ​ $ (0.09) ​ Diluted net income/(loss) per share ​ $ 0.12 ​ $ 0.06 ​ $ (0.09) ​
Schedule of Anti-Dilutive Securities Excluded from Computation of Net Income/(Loss) Per Share	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ 2020 2019 2018 Warrants to purchase common stock ​ ​ — ​ 1,292 ​ 1,600 Options to purchase common stock ​ ​ 592 ​ 2,303 ​ 18,491 Restricted stock units ("RSUs") ​ ​ 1,073 ​ ​ 659 ​ ​ 3,021 Performance stock options ("PSOs") ​ ​ — ​ ​ 2,369 ​ ​ 3,512 Performance stock units ("PSUs") ​ ​ — ​ ​ 38 ​ ​ 711 Employee stock purchase plan ("ESPP") ​ ​ — ​ 369 ​ 283 Total ​ ​ 1,665 ​ ​ 7,030 ​ ​ 27,618 (1) Outstanding PSOs and PSUs for which performance conditions have not been met as of the relevant reporting dates, have not been included in the calculation of the weighted average number of shares used to compute diluted net income/(loss) per share or in the table above.

REVENUE FROM CONTRACTS WITH C_2

REVENUE FROM CONTRACTS WITH CUSTOMERS (Tables)	12 Months Ended
	Dec. 31, 2020
REVENUE FROM CONTRACTS WITH CUSTOMERS
Summary of Revenue from Contracts with Customers	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended ​ ​ December 31, ​ ​ 2020 ​ 2019 ​ 2018 In-App Purchases (over-time revenue recognition) ​ $ 481,279 ​ $ 360,598 ​ $ 316,157 Advertisements and offers (point-in-time revenue recognition) ​ ​ 59,046 ​ ​ 50,728 ​ ​ 50,121 Other (point-in-time revenue recognition) ​ ​ 197 ​ ​ 55 ​ ​ 283 Total revenue ​ $ 540,522 ​ $ 411,381 ​ $ 366,561
Information on Receivables, contract assets and contract liabilities	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2020 ​ December 31, 2019 Receivables, which are included in accounts receivable, net $ 34,571 ​ $ 29,304 Contract liabilities, which are included in deferred revenue 117,672 ​ 97,629

FAIR VALUE MEASUREMENTS (Tables

FAIR VALUE MEASUREMENTS (Tables)	12 Months Ended
	Dec. 31, 2020
FAIR VALUE MEASUREMENTS
Schedule of Assets and Liabilities Presented at Fair Value	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Level 1 Level 2 Level 3 December 31, 2020 Financial Assets ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash and cash equivalents ​ $ 364,396 ​ $ — ​ $ — ​ $ 364,396 ​ Other investments ​ ​ — ​ ​ — ​ ​ 1,565 ​ ​ 1,565 ​ Total financial assets ​ $ 364,396 ​ $ — ​ $ 1,565 ​ $ 365,961 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Level 1 Level 2 Level 3 December 31, 2019 Financial Assets ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash and cash equivalents ​ $ 127,053 ​ $ — ​ $ — ​ $ 127,053 Other investments ​ ​ — ​ ​ — ​ ​ 1,565 ​ ​ 1,565 Total financial assets ​ $ 127,053 ​ $ — ​ $ 1,565 ​ $ 128,618

BALANCE SHEET COMPONENTS (Table

BALANCE SHEET COMPONENTS (Tables)	12 Months Ended
	Dec. 31, 2020
BALANCE SHEET COMPONENTS
Schedule of Components of Accounts Receivable, net	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ 2020 2019 Accounts receivable ​ $ 34,571 ​ $ 29,304 ​ Less: Allowance for doubtful accounts ​ — ​ — ​ Accounts receivable, net ​ $ 34,571 ​ $ 29,304 ​
Schedule of Components of Property and Equipment	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ 2020 2019 Computer equipment ​ $ 10,559 ​ $ 9,079 ​ Furniture and fixtures ​ 3,303 ​ 2,201 ​ Software ​ 3,847 ​ 3,612 ​ Leasehold improvements ​ 16,498 ​ 16,121 ​ Total ​ 34,207 ​ 31,013 ​ Less: Accumulated depreciation and amortization ​ (18,553) ​ (13,370) ​ Property and equipment, net ​ $ 15,654 ​ $ 17,643 ​

GOODWILL AND INTANGIBLE ASSETS

GOODWILL AND INTANGIBLE ASSETS (Tables)	12 Months Ended
	Dec. 31, 2020
GOODWILL AND INTANGIBLE ASSETS
Schedule of Carrying Amounts and Accumulated Amortization of Acquired Intangible Assets	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2020 ​ December 31, 2019 ​ Estimated Gross Accumulated Net Gross Accumulated Net ​ ​ Useful ​ Carrying ​ Amortization ​ Carrying ​ Carrying ​ Amortization ​ Carrying ​ ​ Life ​ Value ​ Expense ​ Value ​ Value ​ Expense ​ Value Intangible assets amortized to cost of revenue: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Titles, content and technology 3 - 5 yrs. ​ $ 21,117 ​ $ (19,617) ​ $ 1,500 ​ $ 21,117 ​ $ (16,359) ​ $ 4,758 ​ ​ ​ ​ ​ $ 21,117 ​ $ (19,617) ​ $ 1,500 ​ $ 21,117 ​ $ (16,359) ​ $ 4,758 ​ ​

LEASES (Tables)

LEASES (Tables)	12 Months Ended
	Dec. 31, 2020
LEASES
Schedule of future minimum lease payments	​ ​ ​ ​ ​ ​ ​ Operating Year Ending December 31, Leases 2021 ​ 7,129 2022 ​ 7,026 2023 ​ ​ 6,980 2024 ​ ​ 5,332 2025 and thereafter ​ ​ 22,335 Total lease payments ​ $ 48,802 Less: imputed interest ​ ​ (9,544) Total ​ $ 39,258
Supplemental Information Operating Cash Flows from Operating Leases	​ ​ ​ ​ ​ ​ December 31, 2020 ​ Weighted average remaining lease term ​ 6.61 yrs. Weighted average discount rate ​ 6.7 % ​ ​ ​ ​ ​ ​ ​ ​ Year Ended ​ December 31, 2020 Cash paid for amounts included in the measurement of lease liabilities: ​ ​ ​ Operating cash outflow from operating leases ​ $ 4,751 ​ ​ ​ ​ ​ ​ ​ ​ Year Ended ​ December 31, 2020 Right of use assets obtained in exchange for new lease obligations: ​ ​ ​ Operating leases ​ $ 407

COMMITMENTS AND CONTINGENCIES (

COMMITMENTS AND CONTINGENCIES (Tables)	12 Months Ended
	Dec. 31, 2020
COMMITMENTS AND CONTINGENCIES
Schedule of Future Unpaid Minimum Guaranteed Royalty Commitments	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Future ​ ​ Minimum ​ ​ Guarantee Year Ending December 31, Commitments 2021 ​ 9,060 2022 ​ ​ 6,881 2023 ​ ​ 6,716 2024 ​ ​ 6,150 Total ​ $ 28,807

STOCKHOLDERS' EQUITY (Tables)

STOCKHOLDERS' EQUITY (Tables)	12 Months Ended
	Dec. 31, 2020
STOCKHOLDERS' EQUITY
Schedule of Warrants Outstanding	Warrants outstanding at December 31, 2020 were as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Number ​ Weighted ​ ​ ​ ​ ​ of Shares ​ Average ​ ​ ​ ​ ​ Outstanding ​ Exercise ​ Average ​ ​ ​ Under ​ Price per ​ Contractual ​ ​ ​ Warrant Share Term (Years) Warrants outstanding, December 31, 2019 ​ 1,600 ​ $ 4.61 ​ 5.44 ​ Exercised ​ (475) ​ $ 4.99 ​ 5.00 ​ Expired ​ (25) ​ $ 4.99 ​ 5.00 ​ Warrants outstanding, December 31, 2020 ​ 1,100 ​ $ 4.44 ​ 5.66 ​
Schedule of estimated the fair value of the warrants	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ 2020 2019 2018 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Dividend yield ​ — % ​ — % ​ — % Risk-free interest rate ​ — % ​ — % ​ 2.53 % Expected volatility ​ — % ​ — % ​ 56.73 % Expected term (in years) ​ — ​ ​ — ​ ​ 3.51 ​

STOCK INCENTIVE AND OTHER BEN_2

STOCK INCENTIVE AND OTHER BENEFIT PLANS (Tables)	12 Months Ended
	Dec. 31, 2020
Summary of Stock Option Activity	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Options Outstanding ​ ​ ​ ​ ​ ​ ​ Weighted Weighted ​ ​ ​ ​ Number ​ Average ​ Average Remaining ​ Aggregate ​ ​ of ​ Exercise ​ Contractual ​ Intrinsic ​ ​ Shares ​ Price ​ Term (Years) ​ Value Balances at December 31, 2017 16,932 $ 2.78 ​ ​ Options granted 6,092 $ 4.82 ​ ​ ​ ​ ​ ​ Options canceled (1,213) $ 3.54 ​ ​ ​ ​ ​ ​ Options exercised (3,320) $ 2.88 ​ ​ ​ ​ ​ ​ Balances at December 31, 2018 18,491 $ 3.39 ​ ​ ​ Options granted 815 $ 7.58 ​ ​ ​ ​ ​ ​ Options canceled (1,219) $ 4.73 ​ ​ ​ ​ ​ ​ Options exercised (1,799) $ 2.81 ​ ​ ​ ​ ​ ​ Balances at December 31, 2019 16,288 $ 3.56 ​ ​ ​ ​ ​ Options granted 210 ​ $ 9.00 ​ ​ ​ ​ ​ ​ Options canceled (489) ​ $ 4.77 ​ ​ ​ ​ ​ ​ Options exercised (4,818) ​ $ 3.23 ​ ​ ​ ​ ​ ​ Balances at December 31, 2020 11,191 ​ $ 3.75 6.51 ​ $ 58,842 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Options exercisable at December 31, 2020 8,897 ​ $ 3.35 6.28 ​ $ 50,343 ​
Schedule of Assumptions Used to Estimate Fair Value of Options	​ ​ ​ ​ ​ ​ ​ ​ Performance Stock Options ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ 2020 2019 2018 Dividend yield — % — % — % Risk-free interest rate — % — % 2.89 % Expected volatility — % — % 60.2 % Expected term (years) — ​ — ​ 5.98 ​ ​ ​ ​ ​ ​ ​ ​ Stock Options ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ 2020 2019 2018 Dividend yield — % — % — % Risk-free interest rate 0.28 % 1.88 % 2.63 % Expected volatility 69.3 % 57.2 % 57.9 % Expected term (years) 4.00 ​ 4.00 ​ 4.00 ​
Schedule of Stock-Based Compensation Expense by Line Item	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ ​ 2020 2019 2018 Research and development ​ $ 19,942 ​ $ 10,466 ​ $ 12,807 ​ Sales and marketing ​ 3,904 ​ 1,700 ​ 2,795 ​ General and administrative ​ 7,963 ​ 5,217 ​ 8,990 ​ Total stock-based compensation expense ​ $ 31,809 ​ $ 17,383 ​ $ 24,592 ​
Schedule of compensation expense related to unvested awards	The following table summarizes total compensation expense related to unvested awards not yet recognized as of December 31, 2020: ​ ​ ​ ​ ​ ​ ​ Unrecognized Compensation ​ ​ Expense for Unvested ​ ​ Awards Stock options ​ $ 5,050 RSUs ​ ​ 36,789 PSUs ​ ​ 3,677 PSOs ​ ​ 325 Total unrecognized compensation expense ​ $ 45,841 (1) The unrecognized compensation expense for PSUs vesting in FY2023 and FY2024 is not included in the table above as the Company does not have a reasonable basis upon which to estimate the vesting probability of such awards in those future periods.
Restricted stock units ("RSUs")
Summary of Company's Performance-based Awards	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted ​ Weighted ​ ​ ​ ​ ​ Number of ​ Average ​ Average Remaining ​ ​ Aggregate ​ ​ Units ​ Grant Date ​ Contractual ​ ​ Intrinsic ​ Outstanding Fair Value ​ Term (Years) ​ ​ Value Awarded and unvested, December 31, 2017 ​ 5,812 ​ $ 2.96 ​ ​ ​ ​ ​ Granted ​ 278 ​ $ 5.90 ​ ​ ​ ​ ​ Vested ​ (2,648) ​ $ 3.24 ​ ​ ​ ​ ​ Forfeited ​ (421) ​ $ 2.71 ​ ​ ​ ​ ​ Awarded and unvested, December 31, 2018 ​ 3,021 ​ $ 3.01 ​ ​ ​ ​ ​ Granted ​ 2,936 ​ $ 6.84 ​ ​ ​ ​ ​ Vested ​ (1,688) ​ $ 3.27 ​ ​ ​ ​ ​ Forfeited ​ (318) ​ $ 4.17 ​ ​ ​ ​ ​ Awarded and unvested, December 31, 2019 3,951 ​ $ 5.66 ​ ​ ​ ​ ​ Granted (1) 4,635 ​ $ 7.29 ​ ​ ​ ​ ​ Vested (1,832) ​ $ 4.92 ​ ​ ​ ​ ​ Forfeited (486) ​ $ 6.15 ​ ​ ​ ​ ​ Awarded and unvested, December 31, 2020 6,268 ​ $ 7.04 ​ 1.62 ​ $ 56,478
Performance stock units ("PSUs")
Summary of Stock Option Activity	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted ​ Weighted ​ ​ ​ ​ ​ Number of ​ Average ​ Average Remaining ​ ​ Aggregate ​ ​ Units ​ Grant Date ​ Contractual ​ ​ Intrinsic ​ Outstanding Fair Value ​ Term (Years) ​ ​ Value Awarded and unvested, December 31, 2017 ​ 661 ​ $ 3.59 ​ ​ ​ ​ ​ Granted ​ 2,909 ​ $ 5.85 ​ ​ ​ ​ ​ Forfeited ​ (40) ​ $ 4.03 ​ ​ ​ ​ ​ Awarded and unvested, December 31, 2018 ​ 3,530 ​ $ 5.45 ​ ​ ​ ​ ​ Granted ​ 2,780 ​ $ 6.46 ​ ​ ​ ​ ​ Vested ​ (700) ​ $ 4.59 ​ ​ ​ ​ ​ Forfeited ​ (193) ​ $ 6.14 ​ ​ ​ ​ ​ Awarded and unvested, December 31, 2019 ​ 5,417 ​ $ 6.06 ​ ​ ​ ​ ​ Granted (1) ​ 1,432 ​ $ 9.53 ​ ​ ​ ​ ​ Vested ​ (1,509) ​ $ 5.64 ​ ​ ​ ​ ​ Forfeited ​ (1,436) ​ $ 6.78 ​ ​ ​ ​ ​ Awarded and unvested, December 31, 2020 ​ 3,904 ​ $ 7.22 ​ 1.38 ​ $ 35,178 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ PSUs expected to vest as of December 31, 2020 ​ 749 ​ $ 6.37 ​ 0.79 ​ $ 6,748
Performance stock options ("PSOs")
Summary of Stock Option Activity	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted ​ Weighted ​ ​ ​ ​ ​ Number of ​ Average ​ Average Remaining ​ ​ Aggregate ​ ​ Shares ​ Exercise ​ Contractual ​ ​ Intrinsic ​ Outstanding Price ​ Term (Years) ​ ​ Value Balance as of December 31, 2017 ​ 4,170 ​ $ 3.59 ​ ​ ​ ​ ​ Granted ​ 2,737 ​ $ 5.87 ​ ​ ​ ​ ​ Forfeited ​ (151) ​ $ 3.59 ​ ​ ​ ​ ​ Balance as of December 31, 2018 ​ 6,756 ​ $ 4.51 ​ ​ ​ ​ ​ Exercised ​ (173) ​ $ 3.59 ​ ​ ​ ​ ​ Balance as of December 31, 2019 ​ 6,583 ​ $ 4.54 ​ ​ ​ ​ ​ Canceled ​ (1,377) ​ $ 6.18 ​ ​ ​ ​ ​ Exercised ​ (1,133) ​ $ 3.61 ​ ​ ​ ​ ​ Balance as of December 31, 2020 ​ 4,073 ​ $ 4.24 ​ 7.04 ​ $ 19,422 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ PSOs expected to vest as of December 31, 2020 ​ 992 ​ $ 4.93 ​ 7.30 ​ $ 4,054 PSOs exercisable at December 31, 2020 ​ 2,615 ​ $ 3.59 ​ 6.80 ​ $ 14,162

INCOME TAXES (Tables)

INCOME TAXES (Tables)	12 Months Ended
	Dec. 31, 2020
INCOME TAXES
Component of Income (Loss) Before Income Taxes By Tax Jurisdiction	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ ​ 2020 2019 2018 United States ​ $ 19,279 ​ $ 7,047 ​ $ (12,396) ​ Foreign ​ ​ 2,307 ​ ​ 2,295 ​ ​ (254) ​ Income (loss) before income taxes ​ $ 21,586 ​ $ 9,342 ​ $ (12,650) ​
Components of Income Tax Benefit/(Provision)	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, Current: 2020 2019 2018 Federal ​ $ (122) ​ $ 373 ​ $ (96) State ​ ​ (161) ​ ​ (10) ​ ​ (8) Foreign ​ ​ (1,105) ​ ​ (590) ​ ​ (500) ​ ​ ​ (1,388) ​ ​ (227) ​ ​ (604) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Deferred: ​ ​ ​ ​ ​ ​ ​ ​ ​ Federal ​ ​ — ​ ​ — ​ ​ — Foreign ​ ​ 249 ​ ​ (244) ​ ​ 55 ​ ​ ​ 249 ​ ​ (244) ​ ​ 55 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total: ​ ​ ​ ​ ​ ​ ​ ​ ​ Federal ​ ​ (122) ​ ​ 373 ​ ​ (96) State ​ ​ (161) ​ ​ (10) ​ ​ (8) Foreign ​ ​ (856) ​ ​ (834) ​ ​ (445) ​ ​ $ (1,139) ​ $ (471) ​ $ (549)
Difference Between Actual Rate and Federal Statutory Rate	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ ​ ​ 2020 ​ 2019 ​ 2018 Tax at federal statutory rate ​ ​ 21.0 % ​ 21.0 % ​ 21.0 % Meals and entertainment ​ ​ 0.3 ​ ​ 3.1 ​ ​ (2.0) ​ Research and development credit ​ ​ (24.4) ​ ​ (41.0) ​ ​ 21.3 ​ Stock-based compensation ​ ​ (24.4) ​ ​ (29.0) ​ ​ 17.9 ​ Revenue from contracts with customers ​ ​ — ​ ​ — ​ ​ (14.6) ​ Others ​ ​ 3.1 ​ ​ (0.6) ​ ​ (3.1) ​ Global intangible low-taxed income ​ ​ 0.8 ​ ​ 4.2 ​ ​ (1.7) ​ Valuation allowance ​ ​ 10.2 ​ ​ 17.5 ​ ​ (35.3) ​ Executive compensation ​ ​ 8.6 ​ ​ 6.1 ​ ​ — ​ Foreign tax credit ​ ​ 8.2 ​ ​ 23.7 ​ ​ (7.8) ​ Other non-deductible expenses ​ ​ 1.9 ​ ​ — ​ ​ — ​ Effective tax rate ​ ​ 5.3 % ​ 5.0 % ​ (4.3) %
Deferred Tax Assets and Liabilities	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2020 ​ December 31, 2019 ​ US Foreign Total US Foreign Total Deferred tax assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fixed assets ​ $ 654 ​ $ 71 ​ $ 725 ​ $ 209 ​ $ 71 ​ $ 280 Net operating loss carryforwards ​ ​ 42,822 ​ ​ 7 ​ ​ 42,829 ​ ​ 48,968 ​ ​ 25 ​ ​ 48,993 Accruals, reserves and other ​ ​ 7,460 ​ ​ 401 ​ ​ 7,861 ​ ​ 3,939 ​ ​ 121 ​ ​ 4,060 Foreign tax credit ​ ​ 1,138 ​ ​ — ​ ​ 1,138 ​ ​ 2,905 ​ ​ — ​ ​ 2,905 Stock-based compensation ​ ​ 5,494 ​ ​ — ​ ​ 5,494 ​ ​ 5,882 ​ ​ — ​ ​ 5,882 Research and development credit ​ ​ 27,899 ​ ​ — ​ ​ 27,899 ​ ​ 22,630 ​ ​ — ​ ​ 22,630 Capitalized research and development ​ ​ 7,784 ​ ​ — ​ ​ 7,784 ​ ​ 7,189 ​ ​ — ​ ​ 7,189 Intangible assets ​ ​ 988 ​ ​ — ​ ​ 988 ​ ​ 355 ​ ​ — ​ ​ 355 Operating lease liabilities ​ ​ 8,708 ​ ​ 155 ​ ​ 8,863 ​ ​ 8,926 ​ ​ 117 ​ ​ 9,043 Other ​ ​ 2,773 ​ ​ — ​ ​ 2,773 ​ ​ 2,951 ​ ​ — ​ ​ 2,951 Total deferred tax assets ​ $ 105,720 ​ $ 634 ​ $ 106,354 ​ $ 103,954 ​ $ 334 ​ $ 104,288 Deferred tax liabilities: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fixed assets ​ $ — ​ $ (68) ​ $ (68) ​ $ — ​ $ (40) ​ $ (40) Operating lease right of use assets ​ ​ (6,961) ​ ​ (144) ​ ​ (7,105) ​ ​ (7,663) ​ ​ (104) ​ ​ (7,767) Net deferred tax assets ​ ​ 98,759 ​ ​ 422 ​ ​ 99,181 ​ ​ 96,291 ​ ​ 190 ​ ​ 96,481 Less valuation allowance ​ ​ (98,759) ​ ​ (7) ​ ​ (98,766) ​ ​ (96,291) ​ ​ (25) ​ ​ (96,316) Net deferred tax assets ​ $ — ​ $ 415 ​ $ 415 ​ $ — ​ $ 165 ​ $ 165
Reconciliation of Total Amounts of Unrecognized Tax Benefits	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ 2020 2019 Beginning balance ​ $ 15,084 ​ $ 20,718 Reductions of tax positions taken during previous years ​ ​ — ​ ​ (8,226) Additions based on uncertain tax positions related to the current period ​ ​ 3,940 ​ ​ 2,598 Additions based on uncertain tax positions related to prior periods ​ ​ 61 ​ ​ — Cumulative translation adjustment ​ ​ — ​ ​ (6) Ending balance ​ $ 19,085 ​ $ 15,084

SEGMENT INFORMATION AND OPERA_2

SEGMENT INFORMATION AND OPERATIONS BY GEOGRAPHIC AREA (Tables)	12 Months Ended
	Dec. 31, 2020
SEGMENT INFORMATION AND OPERATIONS BY GEOGRAPHIC AREA
Schedule of Revenues by Geographic Region	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ ​ 2020 2019 2018 United States of America ​ $ 424,865 ​ $ 320,343 ​ $ 280,264 ​ Americas, excluding the United States ​ 32,003 ​ 25,240 ​ 21,903 ​ EMEA ​ 57,353 ​ 45,700 ​ 41,585 ​ APAC ​ 26,301 ​ 20,098 ​ 22,809 ​ Total revenue ​ $ 540,522 ​ $ 411,381 ​ $ 366,561 ​
Schedule of Long-Lived Assets by Geographic Location	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ 2020 2019 United States of America ​ $ 14,868 ​ $ 16,738 ​ Rest of the World ​ 786 ​ 905 ​ Total ​ $ 15,654 ​ $ 17,643 ​

QUARTERLY FINANCIAL DATA (una_2

QUARTERLY FINANCIAL DATA (unaudited) (Tables)	12 Months Ended
	Dec. 31, 2020
QUARTERLY FINANCIAL DATA (unaudited)
Unaudited Quarterly Consolidated Statements of Operations Data	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the Three Months Ended ​ ​ 2020 ​ 2019 ​ March 31, June 30, September 30, December 31, March 31, June 30, September 30, December 31, ​ ​ ​ ​ Revenue ​ $ 107,274 ​ $ 133,316 ​ $ 158,531 ​ $ 141,401 ​ $ 95,885 ​ $ 95,540 ​ $ 107,077 ​ $ 112,879 Cost of revenue: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Platform commissions, royalties and other ​ ​ 36,974 ​ ​ 46,727 ​ ​ 56,390 ​ ​ 48,204 ​ ​ 33,270 ​ ​ 32,806 ​ ​ 36,758 ​ ​ 38,278 Impairment and amortization of intangible assets ​ ​ 888 ​ ​ 887 ​ ​ 888 ​ ​ 595 ​ ​ 1,252 ​ ​ 1,056 ​ ​ 1,040 ​ ​ 1,039 Total cost of revenue ​ ​ 37,862 ​ ​ 47,614 ​ ​ 57,278 ​ ​ 48,799 ​ ​ 34,522 ​ ​ 33,862 ​ ​ 37,798 ​ ​ 39,317 Gross profit ​ ​ 69,412 ​ ​ 85,702 ​ ​ 101,253 ​ ​ 92,602 ​ ​ 61,363 ​ ​ 61,678 ​ ​ 69,279 ​ ​ 73,562 Operating expenses: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Research and development ​ ​ 29,531 ​ ​ 28,420 ​ ​ 30,778 ​ ​ 30,989 ​ ​ 26,546 ​ ​ 19,736 ​ ​ 22,968 ​ ​ 25,877 Sales and marketing ​ ​ 42,743 ​ ​ 65,203 ​ ​ 42,222 ​ ​ 27,077 ​ ​ 28,105 ​ ​ 35,040 ​ ​ 46,140 ​ ​ 31,013 General and administrative ​ ​ 6,667 ​ ​ 7,266 ​ ​ 7,870 ​ ​ 9,688 ​ ​ 6,635 ​ ​ 4,951 ​ ​ 5,879 ​ ​ 5,751 Total operating expenses ​ ​ 78,941 ​ ​ 100,889 ​ ​ 80,870 ​ ​ 67,754 ​ ​ 61,286 ​ ​ 59,727 ​ ​ 74,987 ​ ​ 62,641 Income/(loss) from operations ​ ​ (9,529) ​ ​ (15,187) ​ ​ 20,383 ​ ​ 24,848 ​ ​ 77 ​ ​ 1,951 ​ ​ (5,708) ​ ​ 10,921 Interest and other income/(expense), net ​ ​ (65) ​ ​ 434 ​ ​ 413 ​ ​ 289 ​ ​ 764 ​ ​ 556 ​ ​ 271 ​ ​ 510 Income/(loss) before income taxes ​ ​ (9,594) ​ ​ (14,753) ​ ​ 20,796 ​ ​ 25,137 ​ ​ 841 ​ ​ 2,507 ​ ​ (5,437) ​ ​ 11,431 Income tax (provision)/benefit ​ ​ 1,321 ​ ​ 6,187 ​ ​ (7,391) ​ ​ (1,256) ​ ​ (178) ​ ​ — ​ ​ 348 ​ ​ (641) Net income/(loss) ​ $ (8,273) ​ $ (8,566) ​ $ 13,405 ​ $ 23,881 ​ $ 663 ​ $ 2,507 ​ $ (5,089) ​ $ 10,790 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income/(loss) per share ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Basic ​ $ (0.06) ​ $ (0.05) ​ $ 0.08 ​ $ 0.14 ​ $ 0.00 ​ $ 0.02 ​ $ (0.03) ​ $ 0.07 Diluted ​ $ (0.06) ​ $ (0.05) ​ $ 0.07 ​ $ 0.13 ​ $ 0.00 ​ $ 0.02 ​ $ (0.03) ​ $ 0.07

THE COMPANY AND SUMMARY OF SI_4

THE COMPANY AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Revenue Recognition (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Cumulative impact to retained earnings (ASC 606)	$ 417,094	$ 203,087	$ 177,313	$ 153,860
Revenue recognized relating to performance obligations satisfied in prior periods	$ 0	$ 0
Revenue, Remaining Performance Obligation, Optional Exemption, Performance Obligation [true false]	true
Number of years revenue from consumable virtual items has been insignificant	3 years
Minimum
Estimated useful life of a paying user	4 months
Maximum
Estimated useful life of a paying user	8 months
Cumulative effect adjustment from adoption of ASU 2014-09
Cumulative impact to retained earnings (ASC 606)				$ 8,826

THE COMPANY AND SUMMARY OF SI_5

THE COMPANY AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Other Estimates and Judgments (Details)	12 Months Ended
	Dec. 31, 2020
THE COMPANY AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
Number of days required to be considered an active user	30 days
Revenue, minimum number of days of data required	120 days

THE COMPANY AND SUMMARY OF SI_6

THE COMPANY AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Concentration Risks (Details)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenues from customers | Apple
Concentration Risk [Line Items]
Concentration risk percentage from customers	56.2	54.4	54.7
Revenues from customers | Google
Concentration Risk [Line Items]
Concentration risk percentage from customers	32.9	33.5	31.3
Accounts Receivable | Customer Concentration Risk | Apple
Concentration Risk [Line Items]
Concentration risk percentage from customers	42.7	47.2
Accounts Receivable | Customer Concentration Risk | Google
Concentration Risk [Line Items]
Concentration risk percentage from customers	28.8	28.5
Accounts Receivable | Customer Concentration Risk | Tapjoy
Concentration Risk [Line Items]
Concentration risk percentage from customers	22	17.8

THE COMPANY AND SUMMARY OF SI_7

THE COMPANY AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Licensor Royalties, Goodwill and Intangible Assets (Details) - USD ($) $ in Thousands	12 Months Ended			36 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2020
Finite-Lived Intangible Assets [Line Items]
Future minimum royalty payments	$ 28,807	$ 40,150		$ 28,807
Impairment charges to cost of revenues	186	457	$ 711
Goodwill impairment charges	$ 0	$ 0		$ 0
Minimum
Finite-Lived Intangible Assets [Line Items]
Intangible assets estimated useful life	3 years
Maximum
Finite-Lived Intangible Assets [Line Items]
Intangible assets estimated useful life	5 years

THE COMPANY AND SUMMARY OF SI_8

THE COMPANY AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Useful Lives (Details)	12 Months Ended
	Dec. 31, 2020
Computer equipment
Property, Plant and Equipment [Line Items]
Property plant and Equipment useful life	3 years
Computer software | Minimum
Property, Plant and Equipment [Line Items]
Property plant and Equipment useful life	2 years
Computer software | Maximum
Property, Plant and Equipment [Line Items]
Property plant and Equipment useful life	3 years
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Property plant and Equipment useful life	3 years

THE COMPANY AND SUMMARY OF SI_9

THE COMPANY AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Internal Use Software (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Internal Use Software [Abstract]
Capitalized internal use software costs	$ 247	$ 1,216	$ 65
Amortization of capitalized software costs	$ 690	$ 809	$ 896
Capitalized software costs
Internal Use Software [Abstract]
Intangible assets estimated useful life	3 years

THE COMPANY AND SUMMARY OF S_10

THE COMPANY AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Advertising Expenses (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Advertising Expenses [Abstract]
Advertising expense	$ 146,207	$ 117,979	$ 95,037

NET INCOME_(LOSS) PER SHARE- Ba

NET INCOME/(LOSS) PER SHARE- Basic and Diluted (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Earnings Per Share, Basic and Diluted [Abstract]
Net income/(loss)	$ 23,881	$ 13,405	$ (8,566)	$ (8,273)	$ 10,790	$ (5,089)	$ 2,507	$ 663	$ 20,447	$ 8,871	$ (13,199)
Shares used to compute net income/(loss) per share:
Weighted average shares used to compute basic net income/(loss) per share									162,521	145,838	141,402
Dilutive potential common shares									10,646	11,545
Weighted average shares used to compute diluted net income/(loss) per share									173,167	157,383	141,402
Basic net income/(loss) per share	$ 0.14	$ 0.08	$ (0.05)	$ (0.06)	$ 0.07	$ (0.03)	$ 0.02	$ 0	$ 0.13	$ 0.06	$ (0.09)
Diluted net income/(loss) per share	$ 0.13	$ 0.07	$ (0.05)	$ (0.06)	$ 0.07	$ (0.03)	$ 0.02	$ 0	$ 0.12	$ 0.06	$ (0.09)

NET INCOME_(LOSS) PER SHARE - A

NET INCOME/(LOSS) PER SHARE - Antidilutive Shares (Details) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti dilutive securities excluded from computation of diluted net loss per share	1,665	7,030	27,618
Warrants to purchase common stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti dilutive securities excluded from computation of diluted net loss per share		1,292	1,600
Options to purchase common stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti dilutive securities excluded from computation of diluted net loss per share	592	2,303	18,491
Restricted stock units ("RSUs")
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti dilutive securities excluded from computation of diluted net loss per share	1,073	659	3,021
Performance stock options ("PSOs")
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti dilutive securities excluded from computation of diluted net loss per share		2,369	3,512
Performance stock units ("PSUs")
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti dilutive securities excluded from computation of diluted net loss per share		38	711
Employee stock purchase plan ("ESPP")
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti dilutive securities excluded from computation of diluted net loss per share		369	283

REVENUE FROM CONTRACTS WITH C_3

REVENUE FROM CONTRACTS WITH CUSTOMERS - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Disaggregation of Revenue [Line Items]
Total Revenue	$ 141,401	$ 158,531	$ 133,316	$ 107,274	$ 112,879	$ 107,077	$ 95,540	$ 95,885	$ 540,522	$ 411,381	$ 366,561
In-App Purchases | Over-time revenue recognition
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers									481,279	360,598	316,157
Advertisements and offers | Point-in-time revenue recognition
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers									59,046	50,728	50,121
Other | Point-in-time revenue recognition
Disaggregation of Revenue [Line Items]
Total Revenue									$ 197	$ 55	$ 283

REVENUE FROM CONTRACTS WITH C_4

REVENUE FROM CONTRACTS WITH CUSTOMERS - Contract Balances (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Contract Balances
Receivables, which are included in accounts receivable, net	$ 34,571	$ 29,304
Contract assets	0	0
Contract liabilities, which are included in deferred revenue	$ 117,672	$ 97,629	$ 85,736

FAIR VALUE MEASUREMENTS (Detail

FAIR VALUE MEASUREMENTS (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	$ 364,396	$ 127,053
Other Investments	1,565	1,565
Total financial assets	365,961	128,618
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	364,396	127,053
Total financial assets	364,396	127,053
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other Investments	1,565	1,565
Total financial assets	$ 1,565	$ 1,565

BALANCE SHEET COMPONENTS - Acco

BALANCE SHEET COMPONENTS - Accounts Receivable (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
BALANCE SHEET COMPONENTS
Accounts receivable	$ 34,571,000	$ 29,304,000
Accounts receivable, net	34,571,000	29,304,000
Bad debts	$ 0	$ 0	$ 0

BALANCE SHEET COMPONENTS - Prop

BALANCE SHEET COMPONENTS - Property and Equipment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 34,207	$ 31,013
Less: Accumulated depreciation and amortization	(18,553)	(13,370)
Property and equipment, net	15,654	17,643
Depreciation [Abstract]
Depreciation	5,421	4,225	$ 3,855
Computer equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	10,559	9,079
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	3,303	2,201
Computer software
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	3,847	3,612
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 16,498	$ 16,121

GOODWILL AND INTANGIBLE ASSET_2

GOODWILL AND INTANGIBLE ASSETS - Intangible Assets (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended			36 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2020
Finite-Lived Intangible Assets
Gross Carrying Value	$ 21,117				$ 21,117				$ 21,117	$ 21,117		$ 21,117
Accumulated Amortization Expense	(19,617)				(16,359)				(19,617)	(16,359)		(19,617)
Total intangible assets	1,500				4,758				1,500	4,758		1,500
Impairment and amortization of intangible assets	595	$ 888	$ 887	$ 888	1,039	$ 1,040	$ 1,056	$ 1,252	3,258	4,387	$ 9,119
Impairment and amortization of intangible assets											$ 9,119
Beginning Balance				$ 116,227					116,227
Impairment									0	0		0
Ending Balance	116,227				116,227				$ 116,227	116,227		116,227
Minimum
Finite-Lived Intangible Assets
Estimated Useful Life									3 years
Maximum
Finite-Lived Intangible Assets
Estimated Useful Life									5 years
Titles, content and technology
Finite-Lived Intangible Assets
Gross Carrying Value	21,117				21,117				$ 21,117	21,117		21,117
Accumulated Amortization Expense	(19,617)				(16,359)				(19,617)	(16,359)		(19,617)
Total intangible assets	$ 1,500				$ 4,758				$ 1,500	$ 4,758		$ 1,500
Titles, content and technology | Minimum
Finite-Lived Intangible Assets
Estimated Useful Life									3 years
Titles, content and technology | Maximum
Finite-Lived Intangible Assets
Estimated Useful Life									5 years

LEASES - Narrative (Details)

LEASES - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Lease terms
Lessee, Operating Lease, Existence of Option to Extend [true false]	true
Longest extension option	6 years
Rent expense	$ 6,307	$ 5,311	$ 5,759
Restricted cash			$ 110
ROU asset adjustment	$ 407
Minimum
Lease terms
Operating leases, remaining lease terms	4 months
Maximum
Lease terms
Operating leases, remaining lease terms	6 years 11 months 1 day

LEASES - Future Minimum Lease P

LEASES - Future Minimum Lease Payments under Noncancelable Leases (Details) $ in Thousands	Dec. 31, 2020USD ($)
LEASES
2021	$ 7,129
2022	7,026
2023	6,980
2024	5,332
2025 and thereafter	22,335
Total lease payments	48,802
Less imputed interest	(9,544)
Total	$ 39,258

LEASES - Supplemental Informati

LEASES - Supplemental Information (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020USD ($)
LEASES
Weighted-average remaining non-cancelable lease term	6 years 7 months 9 days
Weighted-average discount rate	6.70%
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash outflow from operating leases	$ 4,751
Right of use assets obtained in exchange for new lease obligations:
Operating leases	$ 407

COMMITMENTS AND CONTINGENCIES -

COMMITMENTS AND CONTINGENCIES - Future Unpaid Minimum Guaranteed Royalty Commitments (Details) $ in Thousands	Dec. 31, 2020USD ($)
Future unpaid minimum guaranteed royalty commitments
2021	$ 9,060
2022	6,881
2023	6,716
2024	6,150
Total future unpaid minimum guaranteed royalty commitments	$ 28,807

COMMITMENTS AND CONTINGENCIES_2

COMMITMENTS AND CONTINGENCIES - Other Commitments (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Indemnification Agreement | Officers And Directors
Indemnification Agreements [Abstract]
Indemnification liability recorded	$ 0	$ 0
Indemnification Agreement | Digital Storefronts
Indemnification Agreements [Abstract]
Indemnification liability recorded	0	$ 0
Current and long-term liabilities | Agreements With Various Licensors
Other agreements with commitments
Other Commitment	$ 28,807

STOCKHOLDERS' EQUITY - Follow-o

STOCKHOLDERS' EQUITY - Follow-on Public Offering (Details) $ / shares in Units, $ in Thousands	1 Months Ended
	Jun. 30, 2020USD ($)$ / sharesshares
Follow-on Public Offering
Subsidiary, Sale of Stock [Line Items]
Shares issued | shares	17,250
Offering price per share | $ / shares	$ 9.25
Aggregate gross proceeds | $	$ 159,563
Net proceeds after underwriting fees and offering expenses | $	$ 151,773
Follow-on Public Offering, over-allotment option
Subsidiary, Sale of Stock [Line Items]
Shares issued | shares	2,250

STOCKHOLDERS' EQUITY - Warrants

STOCKHOLDERS' EQUITY - Warrants to Purchase Common Stock (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Number of Shares Outstanding Under Warrants
Warrants outstanding, beginning balance	$ 1,600
Number of Shares Outstanding Under Warrant, Exercised	(475)
Number of Shares Outstanding Under Warrant, Expired	(25)
Warrants outstanding, ending balance	$ 1,100	$ 1,600
Weighted Average Exercise Price Per Share
Weighted average exercise price, beginning balance	$ 4.61
Weighted average exercise price, Exercised	4.99
Weighted average exercise price, Expired	4.99
Weighted average exercise price, ending balance	$ 4.44	$ 4.61
Average Contractual Term (Years)
Warrants outstanding, Average Contractual term (Years)	5 years 7 months 28 days	5 years 5 months 8 days
Average contractual term, Exercised	5 years
Average contractual term, Expired	5 years
Warrants to purchase common stock
Average Contractual Term (Years)
Recognized expense with respect to warrants	$ 0	$ 0	$ 1,046,000

STOCKHOLDERS' EQUITY - Weighted

STOCKHOLDERS' EQUITY - Weighted Average Assumptions (Details) - Warrants to purchase common stock	12 Months Ended
	Dec. 31, 2018
Warrants and Rights Note Disclosure [Abstract]
Risk-free interest rate	2.53%
Expected volatility	56.73%
Expected term (years)	3 years 6 months 3 days

STOCK INCENTIVE AND OTHER BEN_3

STOCK INCENTIVE AND OTHER BENEFIT PLANS (Details) - shares	1 Months Ended	12 Months Ended
	Apr. 30, 2017	Dec. 31, 2020	Dec. 31, 2007	Apr. 30, 2020	Apr. 30, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Contractual term		10 years
Common stock, reserved for future issuance		34,468,000
Options to purchase common stock | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Contractual term		6 years
Options to purchase common stock | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Contractual term		10 years
Performance stock options ("PSOs")
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Contractual term		10 years
Sixth Amendment 2007 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, reserved for future issuance				7,000
Number of shares available for grant		7,459,000
2007 Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock authorized for issuance, increased	4,000,000
Purchase price equal to fair market value, percent			85.00%
Common stock, reserved for future issuance			667,000
Number of shares available for grant		2,003,000
2018 Equity Inducement Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, reserved for future issuance		194,000			400

STOCK INCENTIVE AND OTHER BEN_4

STOCK INCENTIVE AND OTHER BENEFIT PLANS - RSU and PSU Activity (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	1 Months Ended	12 Months Ended
	Nov. 30, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Restricted stock units ("RSUs")
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awarded and unvested, Number of Units Outstanding, beginning balance		3,951	3,021	5,812
Granted, Number of Units Outstanding	293	4,635	2,936	278
Vested, Number of Units Outstanding		(1,832)	(1,688)	(2,648)
Forfeited, Number of Units Outstanding		(486)	(318)	(421)
Awarded and unvested, Number of Units Outstanding, ending balance		6,268	3,951	3,021
Awarded and unvested, Weighted Average Grant Date Fair Value, beginning balance		$ 5.66	$ 3.01	$ 2.96
Granted, Weighted Average Grant Date Fair Value		7.29	6.84	5.90
Vested, Weighted Average Grant Date Fair Value		4.92	3.27	3.24
Forfeited, Weighted Average Grant Date Fair Value		6.15	4.17	2.71
Awarded and unvested, Weighted Average Grant Date Fair Value, ending balance		$ 7.04	$ 5.66	$ 3.01
Awarded and unvested, Weighted Average Remaining Contractual Term (Years)		1 year 7 months 13 days
Aggregate Intrinsic Value	$ 2,638	$ 56,478
Performance stock units ("PSUs")
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awarded and unvested, Number of Units Outstanding, beginning balance		5,417	3,530	661
Granted, Number of Units Outstanding	444	1,432	2,780	2,909
Vested, Number of Units Outstanding		(1,509)	(700)
Forfeited, Number of Units Outstanding		(1,436)	(193)	(40)
Awarded and unvested, Number of Units Outstanding, ending balance		3,904	5,417	3,530
Expected to vest, Number of Units Outstanding		749
Awarded and unvested, Weighted Average Grant Date Fair Value, beginning balance		$ 6.06	$ 5.45	$ 3.59
Granted, Weighted Average Grant Date Fair Value		9.53	6.46	5.85
Vested, Weighted Average Grant Date Fair Value		5.64	4.59
Forfeited, Weighted Average Grant Date Fair Value		6.78	6.14	4.03
Awarded and unvested, Weighted Average Grant Date Fair Value, ending balance		7.22	$ 6.06	$ 5.45
Expected to vest, Weighted Average Grant Date Fair Value		$ 6.37
Awarded and unvested, Weighted Average Remaining Contractual Term (Years)		1 year 4 months 17 days
Expected to vest, Weighted Average Remaining Contractual Term (Years)		9 months 14 days
Aggregate Intrinsic Value	$ 3,997	$ 35,178
Expected to vest, Aggregate Intrinsic Value		$ 6,748

STOCK INCENTIVE AND OTHER BEN_5

STOCK INCENTIVE AND OTHER BENEFIT PLANS - PSO and Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Performance stock options ("PSOs")
Number of Shares Outstanding, beginning balances	6,583,000	6,756,000	4,170,000
Options granted, number of shares	0	0	2,737,000
Number of Shares Outstanding, Canceled	(1,377,000)		(151,000)
Number of Shares Outstanding, Exercised	(1,133,000)	(173,000)
Number of Shares Outstanding, ending balances	4,073,000	6,583,000	6,756,000
Number of Shares Outstanding, expected to vest	992,000
Number of Shares Outstanding, exercisable	2,615,000
Weighted Average Exercise Price, beginning balance	$ 4.54	$ 4.51	$ 3.59
Options granted, weighted average exercise price			5.87
Weighted Average Exercise Price, Canceled	6.18		3.59
Weighted Average Exercise Price, Exercised	3.61	3.59
Weighted Average Exercise Price, ending balance	4.24	$ 4.54	$ 4.51
Weighted Average Exercise Price, expected to vest	4.93
Weighted Average Exercise Price, exercisable	$ 3.59
Weighted Average Remaining Contractual Term, ending balance	7 years 14 days
Weighted Average Remaining Contractual Term, expected to vest	7 years 3 months 18 days
Weighted Average Remaining Contractual Term, exercisable	6 years 9 months 18 days
Aggregate Intrinsic Value, ending balance	$ 19,422
Aggregate Intrinsic Value, expected to vest	4,054
Aggregate Intrinsic Value, exercisable	$ 14,162
Options to purchase common stock
Number of Shares Outstanding, beginning balances	16,288,000	18,491,000	16,932,000
Options granted, number of shares	210,000	(815,000)	6,092,000
Number of Shares Outstanding, Canceled	(489,000)	(1,219,000)	(1,213,000)
Number of Shares Outstanding, Exercised	(4,818,000)	(1,799,000)	(3,320,000)
Number of Shares Outstanding, ending balances	11,191,000	16,288,000	18,491,000
Number of Shares Outstanding, exercisable	8,897,000
Weighted Average Exercise Price, beginning balance	$ 3.56	$ 3.39	$ 2.78
Options granted, weighted average exercise price	9	7.58	4.82
Weighted Average Exercise Price, Canceled	4.77	4.73	3.54
Weighted Average Exercise Price, Exercised	3.23	2.81	2.88
Weighted Average Exercise Price, ending balance	3.75	$ 3.56	$ 3.39
Weighted Average Exercise Price, exercisable	$ 3.35
Weighted Average Remaining Contractual Term, ending balance	6 years 6 months 3 days
Weighted Average Remaining Contractual Term, exercisable	6 years 3 months 10 days
Aggregate Intrinsic Value, ending balance	$ 58,842
Aggregate Intrinsic Value, exercisable	$ 50,343

STOCK INCENTIVE AND OTHER BEN_6

STOCK INCENTIVE AND OTHER BENEFIT PLANS - Weighted Average Assumptions (Details) - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Stock Based Compensation Additional Details
Contractual term	10 years
Performance stock options ("PSOs")
Black-Sholes Valuation Assumptions
Risk-free interest rate			2.89%
Expected volatility			60.20%
Expected term (years)			5 years 11 months 23 days
Stock Based Compensation Additional Details
Contractual term	10 years
Weighted-average fair value of stock options granted			$ 3.38
Granted (in shares)	0	0	2,737,000
Options to purchase common stock
Black-Sholes Valuation Assumptions
Risk-free interest rate	0.28%	1.88%	2.63%
Expected volatility	69.30%	57.20%	57.90%
Expected term (years)	4 years	4 years	4 years
Stock Based Compensation Additional Details
Weighted-average fair value of stock options granted	$ 4.63	$ 3.44	$ 2.25
Granted (in shares)	210,000	(815,000)	6,092,000
Options to purchase common stock | Minimum
Stock Based Compensation Additional Details
Contractual term	6 years
Options to purchase common stock | Maximum
Stock Based Compensation Additional Details
Contractual term	10 years

STOCK INCENTIVE AND OTHER BEN_7

STOCK INCENTIVE AND OTHER BENEFIT PLANS - Stock-Based Compensation Expense (Details) - USD ($) $ / shares in Units, shares in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense	$ 31,809,000	$ 17,383,000	$ 24,592,000
Reversal of stock based compensation expense		2,455,000
Total compensation expense related to unvested awards not yet recognized	$ 45,841,000
Quoted closing price of Company's common stock	$ 9.01
Cash proceeds, net of taxes from option exercises	$ 19,463,000	3,305,000	5,643,000
2007 Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense	$ 1,832,000	1,360,000	927,000
Number of shares available for grant	2,003
Research and development
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense	$ 19,942,000	10,466,000	12,807,000
Sales and marketing
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense	3,904,000	1,700,000	2,795,000
General and administrative
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense	7,963,000	5,217,000	8,990,000
Options to purchase common stock
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense	6,068,000	7,043,000	6,386,000
Total compensation expense related to unvested awards not yet recognized	$ 5,050,000
Unrecognized compensation expense recognized over weighted average period	1 year 3 months 3 days
Total intrinsic value exercised	$ 23,991,000	7,806,000	10,957,000
Significant income tax benefit from stock option exercises	$ 0	0	0
Restricted stock units ("RSUs")
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Vesting period	4 years
Vesting percentage on or around the one-year anniversary	25.00%
Total stock-based compensation expense	$ 11,177,000	6,559,000	8,084,000
Total compensation expense related to unvested awards not yet recognized	$ 36,789,000
Unrecognized compensation expense recognized over weighted average period	3 years 2 months 12 days
Performance stock options ("PSOs")
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense	$ 12,732,000	$ 2,421,000	$ 9,195,000
Total compensation expense related to unvested awards not yet recognized	$ 325,000
Unrecognized compensation expense recognized over weighted average period	1 month 17 days
Performance stock units ("PSUs")
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense	$ 739,000
Total compensation expense related to unvested awards not yet recognized	$ 3,677,000
Unrecognized compensation expense recognized over weighted average period	6 months 7 days

INCOME TAXES - Components by Ju

INCOME TAXES - Components by Jurisdiction (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Extraordinary Items, Noncontrolling Interest [Abstract]
United States									$ 19,279	$ 7,047	$ (12,396)
Foreign									2,307	2,295	(254)
Income/(loss) before income taxes	$ 25,137	$ 20,796	$ (14,753)	$ (9,594)	$ 11,431	$ (5,437)	$ 2,507	$ 841	$ 21,586	$ 9,342	$ (12,650)

INCOME TAXES - Components of In

INCOME TAXES - Components of Income Tax Benefit/(Expense) (Details) - USD ($) $ in Thousands	3 Months Ended							12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Current:
Federal								$ (122)	$ 373	$ (96)
State								(161)	(10)	(8)
Foreign								(1,105)	(590)	(500)
Current Income Tax Expense (Benefit), Total								(1,388)	(227)	(604)
Deferred:
Foreign								249	(244)	55
Deferred Income Tax Expense (Benefit), Total								249	(244)	55
Total:
Federal								(122)	373	(96)
State								(161)	(10)	(8)
Foreign								(856)	(834)	(445)
Income tax benefit/(provision)	$ (1,256)	$ (7,391)	$ 6,187	$ 1,321	$ (641)	$ 348	$ (178)	$ (1,139)	$ (471)	$ (549)

INCOME TAXES - Income Tax Rate

INCOME TAXES - Income Tax Rate Reconciliation (Details)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Effective Income Tax Rate Reconciliation, Percent [Abstract]
Tax at federal statutory rate	21.00%	21.00%	21.00%
Meals and entertainment	0.30%	3.10%	(2.00%)
Research and development credit	(24.40%)	(41.00%)	21.30%
Stock-based compensation	(24.40%)	(29.00%)	17.90%
Revenue from contracts with customers			(14.60%)
Others	3.10%	(0.60%)	(3.10%)
Global intangible low-taxed income	0.80%	4.20%	(1.70%)
Valuation allowance	10.20%	17.50%	(35.30%)
Executive compensation	8.60%	6.10%
Foreign tax credit	8.20%	23.70%	(7.80%)
Other non-deductible expenses	1.90%
Effective tax rate	5.30%	5.00%	(4.30%)

INCOME TAXES - Deferred Tax Ass

INCOME TAXES - Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Deferred tax assets:
Fixed assets	$ 725	$ 280
Net operating loss carryforwards	42,829	48,993
Accruals, reserves and other	7,861	4,060
Foreign tax credit	1,138	2,905
Stock-based compensation	5,494	5,882
Research and development credit	27,899	22,630
Capitalized research and development	7,784	7,189
Intangible assets	988	355
Operating lease liabilities	8,863	9,043
Other	2,773	2,951
Total deferred tax assets	106,354	104,288
Deferred tax liabilities:
Fixed assets	(68)	(40)
Operating lease right of use assets	(7,105)	(7,767)
Net deferred tax assets	99,181	96,481
Less valuation allowance	(98,766)	(96,316)
Net deferred tax assets	415	165
US
Deferred tax assets:
Fixed assets	654	209
Net operating loss carryforwards	42,822	48,968
Accruals, reserves and other	7,460	3,939
Foreign tax credit	1,138	2,905
Stock-based compensation	5,494	5,882
Research and development credit	27,899	22,630
Capitalized research and development	7,784	7,189
Intangible assets	988	355
Operating lease liabilities	8,708	8,926
Other	2,773	2,951
Total deferred tax assets	105,720	103,954
Deferred tax liabilities:
Operating lease right of use assets	(6,961)	(7,663)
Net deferred tax assets	98,759	96,291
Less valuation allowance	(98,759)	(96,291)
Foreign Tax Authority
Deferred tax assets:
Fixed assets	71	71
Net operating loss carryforwards	7	25
Accruals, reserves and other	401	121
Operating lease liabilities	155	117
Total deferred tax assets	634	334
Deferred tax liabilities:
Fixed assets	(68)	(40)
Operating lease right of use assets	(144)	(104)
Net deferred tax assets	422	190
Less valuation allowance	(7)	(25)
Net deferred tax assets	$ 415	$ 165

INCOME TAXES - Additional Infor

INCOME TAXES - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Income Tax Contingency [Line Items]
Accumulated earnings of foreign subsidiaries	$ 3,734
Valuation allowance movements	2,450	$ 2,334
Federal Tax
Income Tax Contingency [Line Items]
Net operating loss carryforwards	182,400
U S State
Income Tax Contingency [Line Items]
Net operating loss carryforwards	90,547
Federal Research And Development Credits | Research and Development Tax Credit Carryforward
Income Tax Contingency [Line Items]
Tax credit carryforward amount	19,515
California Research And Development Tax Credit | Research and Development Tax Credit Carryforward
Income Tax Contingency [Line Items]
Tax credit carryforward amount	28,010
Foreign Tax Authority
Income Tax Contingency [Line Items]
Tax credit carryforward amount	$ 1,128

INCOME TAXES - Unrecognized tax

INCOME TAXES - Unrecognized tax benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Reconciliation of total amounts of unrecognized tax benefits
Unrecognized Tax Benefits, Beginning Balance	$ 15,084	$ 20,718
Reductions of tax positions taken during previous years		(8,226)
Additions based on uncertain tax positions related to the current period	3,940	2,598
Additions based on uncertain tax positions related to prior periods	61
Cumulative translation adjustment		(6)
Unrecognized Tax Benefits, Ending Balance	19,085	15,084
Unrecognized tax benefit netted against deferred tax assets	$ 19,035	$ 15,084

SEGMENT INFORMATION AND OPERA_3

SEGMENT INFORMATION AND OPERATIONS BY GEOGRAPHIC AREA - Revenue (Details) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020USD ($)	Sep. 30, 2020USD ($)	Jun. 30, 2020USD ($)	Mar. 31, 2020USD ($)	Dec. 31, 2019USD ($)	Sep. 30, 2019USD ($)	Jun. 30, 2019USD ($)	Mar. 31, 2019USD ($)	Dec. 31, 2020USD ($)segment	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Long-lived assets (primarily consist of property and equipment)
Number of Operating Segments | segment									1
Revenues	$ 141,401	$ 158,531	$ 133,316	$ 107,274	$ 112,879	$ 107,077	$ 95,540	$ 95,885	$ 540,522	$ 411,381	$ 366,561
United States of America
Long-lived assets (primarily consist of property and equipment)
Revenues									424,865	320,343	280,264
Americas, excluding the United States
Long-lived assets (primarily consist of property and equipment)
Revenues									32,003	25,240	21,903
EMEA
Long-lived assets (primarily consist of property and equipment)
Revenues									57,353	45,700	41,585
APAC
Long-lived assets (primarily consist of property and equipment)
Revenues									$ 26,301	$ 20,098	$ 22,809

SEGMENT INFORMATION AND OPERA_4

SEGMENT INFORMATION AND OPERATIONS BY GEOGRAPHIC AREA - Long-Lived Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Long-lived assets (primarily consist of property and equipment)
Long-Lived Assets	$ 15,654	$ 17,643
United States of America
Long-lived assets (primarily consist of property and equipment)
Long-Lived Assets	14,868	16,738
Rest of the World
Long-lived assets (primarily consist of property and equipment)
Long-Lived Assets	$ 786	$ 905

SUBSEQUENT EVENTS (Details)

SUBSEQUENT EVENTS (Details) - Subsequent Event	Feb. 08, 2021USD ($)$ / shares
Subsequent Event [Line Items]
Cash for each share of Company's stock issued and outstanding, Merger Agreement | $ / shares	$ 12.50
Enterprise value, Merger Agreement | $	$ 2,100,000

QUARTERLY FINANCIAL DATA (una_3

QUARTERLY FINANCIAL DATA (unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
QUARTERLY FINANCIAL DATA (unaudited)
Revenues	$ 141,401	$ 158,531	$ 133,316	$ 107,274	$ 112,879	$ 107,077	$ 95,540	$ 95,885	$ 540,522	$ 411,381	$ 366,561
Cost of revenue:
Platform commissions, royalties and other	48,204	56,390	46,727	36,974	38,278	36,758	32,806	33,270	188,295	141,112	129,156
Impairment and amortization of intangible assets	595	888	887	888	1,039	1,040	1,056	1,252	3,258	4,387	9,119
Total cost of revenue	48,799	57,278	47,614	37,862	39,317	37,798	33,862	34,522	191,553	145,499	138,275
Gross profit	92,602	101,253	85,702	69,412	73,562	69,279	61,678	61,363	348,969	265,882	228,286
Operating expenses:
Research and development	30,989	30,778	28,420	29,531	25,877	22,968	19,736	26,546	119,718	95,127	95,174
Sales and marketing	27,077	42,222	65,203	42,743	31,013	46,140	35,040	28,105	177,245	140,298	113,860
General and administrative	9,688	7,870	7,266	6,667	5,751	5,879	4,951	6,635	31,491	23,216	31,667
Total operating expenses	67,754	80,870	100,889	78,941	62,641	74,987	59,727	61,286	328,454	258,641	240,701
Income/(loss) from operations	24,848	20,383	(15,187)	(9,529)	10,921	(5,708)	1,951	77	20,515	7,241	(12,415)
Interest and other income/(expense), net	289	413	434	(65)	510	271	556	764	1,071	2,101	(235)
Income/(loss) before income taxes	25,137	20,796	(14,753)	(9,594)	11,431	(5,437)	2,507	841	21,586	9,342	(12,650)
Income tax (provision)/benefit	(1,256)	(7,391)	6,187	1,321	(641)	348		(178)	(1,139)	(471)	(549)
Net income/(loss)	$ 23,881	$ 13,405	$ (8,566)	$ (8,273)	$ 10,790	$ (5,089)	$ 2,507	$ 663	$ 20,447	$ 8,871	$ (13,199)
Net income/(loss) per share
Basic net income/(loss) per share	$ 0.14	$ 0.08	$ (0.05)	$ (0.06)	$ 0.07	$ (0.03)	$ 0.02	$ 0	$ 0.13	$ 0.06	$ (0.09)
Diluted net income/(loss) per share	$ 0.13	$ 0.07	$ (0.05)	$ (0.06)	$ 0.07	$ (0.03)	$ 0.02	$ 0	$ 0.12	$ 0.06	$ (0.09)