Gravity Sling, developed by Riptide Games, is a physics-based game set in outer space. You play as an astronaut floating in the zero gravity vacuum, and you must use a single boost to propel yourself back to your ship. Succeed, and you move on to the next level. Miss, and you end up like Tim Robbins in Mission to Mars.
Using an intuitive swipe motion, you set the angle and power of the thrust, like you would in a minigolf game. However, planets of various sizes are also nearby, and their gravitational effects must be taken into account. For instance, if you plot your course right, you can sling yourself from the gravity of one planet into the gravity of another, and loop around it into your ship.
If you miscalculate and crash into a planet, the original arrow you drew with your swipe remains on the screen to help you calculate your next attempt. The longer the path you make your astronaut travel before meeting your ship, the higher your score. OpenFeint tracks the leaderboards and awards achievements.
Another cool thing about Gravity Sling is that it will be one of the first games to be released as a free download, with additional content available as an in-app purchase. The free version will feature 15 levels, which will be more than enough for you to determine whether or not the game appeals to you. The in-app purchase is a level pack that will cost $0.99 and will consist of 30 additional stages.
This game has already been submitted to the App Store, so look for it in the coming week.