Want to know what'd be cool? A free roam game where that you are a ghost, and you can just jump from person to person. Have you be good or evil, by the choices you make, and if your "host" dies, you are judged, and can go to heaven, where you can choose to come back, or Hell, where you'd have to escape. Kinda a game like gangstar, where you can choose all sorts of missions. But, this is more of a Xbox 360/ PS3 game. Hmmm....
Maybe a game that starts you off as a comic book character. You are a stick figure trying to find something like your way home and run in to trouble. Make it a platformer and name it stick adventures or something unique like you said. I would def. buy. You could also make it episodic if that's a word. Idk
Magic: The Gathering/ Orions-like collectible card game, since Chillingo is dropping support and updates for Orions (except for two add on expansions in the unknown future, lowest priority according to the dev in another thread). Solid fan base. Easy implementation. In-app sales of special powerup cards/expansions. Think about it, and Good Luck!