Gravity Runner is a little game put together by a group called We Are Colin -- it's a side-scrolling platformer with, as the name implies, a gravity defying twist. The idea is that after tapping to jump as your little character runs along, you can tap again to switch his gravity, and start running on the ceiling rather than the floor. As you might expect, the game gets tough fast -- not only is the speed uncontrollable (the game is somewhat forgiving, as hitting obstacles will usually get your guy to stop rather than actually kill him), but the jumping is kind of "floaty," requiring split-second timing even early on in the game's 25 plus stages.
There's also an endless mode to play with, and OpenFeint functionality adds leaderboards and achievements to the mix as well. Gravity Runner isn't really playing around -- just a few stages in, you'll have to depend on both quick timing and a little bit of thought about which way your guy is headed. But it's an excellent platformer that eventually turns into a puzzle game, as you try to see just how to get your character jumping up where he needs to be. At its current price of just 99 cents, Gravity Runner has a nice retro charm that's worth the buck.