Rage and Rage HD Free, But Who Knows For How Long

"Rage is a first person shooter for iOS where you blast your way through mutants in some post-apocalyptic disaster, it's fairly similar to classics Doom and Quake, and that's because ID Software created them all."

This game is a heck of a lot of fun if you are into the FPS style games. Even if you aren't, you might enjoy the fact that it is currently free. You can also get the regular version but why not go with the HD, it's universal.