Amazon made its first push into in-house game development this summer with the launch of Amazon Game Studios and its first title, the Facebook-bound Living Classics, and its now made its second big move. The company announced today that its first mobile game, Air Patriots, is now available for iOS, Android and Kindle Fire devices (and free on each, albeit with in-app purchases). Not surprisingly, Amazon has paid particular attention to the Kindle Fire version, taking advantage of GameCircle to track achievements and high scores, as well as Whispersync to let you save your progress on one device and pick up where you left off on another. As for the game itself, Amazon says it's a "new kind of tower defense game," with players drawing a path for the planes to fend off the oncoming tanks. Head on past the break for a quick video.