Tap Tap Revenge 4, one of the more popular games on iOS, is now available on Android. Think of TTR as Rock Band for your fingers, only you are just tapping along to the beat or lyrics rather than attempting to play an instrument. The game has current hits from a variety of artists, 3D graphics, a chatting platform, global leaderboards, arcade modes, battles, custom avatars and weekly contests. This is a real deal mobile game. Free.