According to Tech Crunch, Amazon is working on a new project called "unlocked", which will offer applications and in-app purchaces from the Android apps fee free. Among the developers who participate in the program, find the Sega America and Monument Valley, offering free titles Sonic Dash and UsTwo respectively. The developer will be able to withdraw from the program without the application be removed from the Appstore Amazon, simply turned into application fee. So Amazon is hoping to attract other users in the Appstore, which already counts 400,000 applications.

Source:
http://techcrunch.com/2015/03/20/ama...d/#j67oKE:RcD4