Shortly after replaying Terry Cavanagh's VVVVVV one evening, I put together a prototype of a gravity-switching platform game - one where you had four possible directions for gravity instead of just two. It took me a while to decide where I was going with it, but after some encouragement to put it on the iPhone and use its gravity detection properties, it gradually turned into a complete game.
To separate it from its inspiration, I wanted it to be more of a puzzle game than a platformer, with the challenge being based around getting quickly and efficiently through the levels, just by relying on one ability that you're forced to use in more and more ways over the course of the game. Your only form of control in this game is changing the direction of gravity, and you have to use this well to guide the perpetually running stickman through the increasingly dangerous graph-paper levels.
The full game ($0.99 on the App Store) has seventy levels, and there's also a free version with fifteen further unique ones. On top of that, the free edition also has a Flash version which you can play on the game's site.