The Amazon Underground app for Android launched today. Amazon said it is offering $10,000 worth of apps and items for free through Underground. Users that want the app will have to download it directly from the Amazon Appstore, as Google Play does not currently support it. The apps and games on Underground are automatically available on Fire HD and Fire HDX tablets.

Free versions of popular premium titles like OfficeSuite Professional 8, Goat Simulator, and PhotoSuite 4 are available through Amazon Underground. Titles with in-app purchases, like Frozen Free Fall, Star Wars: Rebels — Recon Missions, Angry Birds: Slingshot Stella, and Looney Tunes Dash, are also available through the new app. According to Gadgtspot, Amazon also got rid of its Free App of the Day, which is likely related to the launch of Underground.

In the games and apps available in Amazon Underground, the in-app items, which are usually available for purchase, are available for free. Amazon has marked the apps and games with a banner that reads “actually free.” Amazon said in a statement, “Many apps that are marked as ‘free’ turn out not to be completely free. They use in-app purchases to charge you for special items or unlock new features or levels.”

Many companies are struggling with microtransactions in the free-to-play business model currently adopted for most apps and games. With this business model, players can get a game or app for free and then pay for in-app items to use more features of the product. However, studies have shown that only a small percentage of the users that download a so-called free app or game ever pay anything to use it.

The developers of those apps and games will be compensated by Amazon based on pay per usage. In exchange for waiving their normal in-app fees, app and game developers are paid a certain amount on a per-minute-played basis. Amazon claims that the Underground app is a long-term project, and not a one-time promotion. If the new model takes off, it could provide an interesting path to increased revenues for game and app developers. The success of the app will depend entirely on the quality of the free apps it offers.