Stan Lee is the Grandad everyone wishes they had. Well, that might not be true, you probably love your Granddad loads. But anyway, the point remains -- Stan Lee is a cool old guy, and he's continuing to up that cool quotient by getting involved in iOS development.
The game is called Verticus, and is a 3D play on the endless runner thing. Except, instead of endlessly running, you are endlessly falling.
Stan Lee contributed a lot of the ideas for the story and the characters, and actually provided the voiceover for this trailer. He also voices the Mission Commander in the game itself.