Cap'n Code has released Star Stepper, a platform jumper game for Windows Phone 7. The game has you helping Astro Joe escape a gravity well by working his way up your Windows Phone screen.
The higher you go, the higher your score. There are dangers involved, other than falling, that include bombs, asteroids, rockets and such.
You maneuver Astro Joe by tilting your Windows Phone from side to side. You can also give Astro Joe a rocket boost by tapping the screen. With the rocket boosts, you also surround Joe with a force field making him invulnerable to the dangers of deep space. The Windows Phone 7 game also includes a world wide leaderboard to let you share and compare your scores with other players.
Star Stepper is a free game for your Windows Phone and you can download it here (opens Zune) at the Marketplace.