Summary of Significant Accounting Policies - Narrative (Details) $ / shares in Units, $ in Thousands			3 Months Ended		9 Months Ended
	Dec. 16, 2020 $ / shares shares	Mar. 02, 2020 $ / shares shares	Sep. 30, 2021 USD ($) $ / shares shares	Sep. 30, 2020 USD ($)	Sep. 30, 2021 USD ($) segement $ / shares shares	Sep. 30, 2020 USD ($)	Mar. 31, 2021 $ / shares	Dec. 31, 2020 USD ($)
Concentration Risk [Line Items]
Reduction to revenue, end-user incentives | $			$ 18,700	$ 13,000	$ 54,900	$ 36,600
Sales and marketing expense, end-user incentive | $			47,000	24,200	122,600	61,400
Engagement expense | $			50,000	26,600	130,900	67,200
Restricted cash included in other long-term assets | $			2,920	2,900	$ 2,920	2,900		$ 2,920
Number of operating segments | segement					1
Advertising costs | $			$ 55,200	$ 43,600	$ 156,600	96,200
Remeasurement of redeemable convertible preferred stock | $					$ 0	$ 865,952
Number of shares issued in private placement (in shares)	15,853,052	69,000,000			10,033,333
Number of warrants per unit (in shares)	0.25
Stock sold, price per share (in dollars per share) | $ / shares	$ 10.00	$ 10.00					$ 23.34
Warrant exercise price (in dollars per share) | $ / shares			$ 11.50		$ 11.50
Warrants forfeited (in shares)					5,016,666
Expected dividend yield					0.00%
Minimum
Concentration Risk [Line Items]
Weighted Average Remaining Useful Life (in years)					1 year
Maximum
Concentration Risk [Line Items]
Weighted Average Remaining Useful Life (in years)					8 years
Sponsor
Concentration Risk [Line Items]
Warrants forfeited (in shares)	5,016,666
Public Warrant
Concentration Risk [Line Items]
Number of shares issued in private placement (in shares)		17,250,000,000,000
Warrant exercise price (in dollars per share) | $ / shares		$ 11.50
Warrants outstanding (in shares)			0		0
Private Warrant
Concentration Risk [Line Items]
Number of shares issued in private placement (in shares)		10,033,333
Stock sold, price per share (in dollars per share) | $ / shares		$ 1.50
Warrants outstanding (in shares)			4,535,728		4,535,728
Class A common stock, par value $0.0001 per share
Concentration Risk [Line Items]
Number of shares per unit (in shares)		1
Number of shares called by each warrant (in shares)		1	1		1
Class A common stock, par value $0.0001 per share | Public Warrant
Concentration Risk [Line Items]
Number of shares called by each warrant (in shares)		1
Class A common stock, par value $0.0001 per share | Private Warrant
Concentration Risk [Line Items]
Number of shares called by each warrant (in shares)		1
Revenue | Customer Concentration Risk | Game Developer A
Concentration Risk [Line Items]
Concentration risk, percentage (less than)			43.00%	56.00%	43.00%	63.00%
Revenue | Customer Concentration Risk | Game Developer B
Concentration Risk [Line Items]
Concentration risk, percentage (less than)			37.00%	31.00%	39.00%	25.00%
Revenue | Geographic Concentration Risk | Non-US
Concentration Risk [Line Items]
Concentration risk, percentage (less than)			12.00%	10.00%	12.00%	10.00%