Tapjoy

Tapjoy, also recently acquired by Unity, practically invented the "Offerwall" monetization model. Instead of randomly showing ads to users, an Offerwall is a dedicated store inside an app where users can earn premium currency by completing specific actions for third-party advertisers. For example, a player might need 500 "Gems" to buy a new sword in a game. They can either pay $5 real money, or open the Tapjoy Offerwall. The Offerwall will present them with tasks: "Download this casino app and reach level 5 to earn 200 Gems," or "Sign up for a free trial of this streaming service to earn 500 Gems." When the user completes the task, the advertiser pays the game developer a massive bounty (sometimes $5 to $10 per completion), making it the highest-paying ad format in the industry. This opt-in, high-reward system is incredibly popular among "freemium" users who refuse to spend real money but have plenty of free time. It allows developers to monetize the 95% of their user base that never makes an In-App Purchase (IAP), turning non-paying users into significant revenue generators without compromising the core gameplay loop.