Halfbrick's latest game actually started its life on the PlayStation Network as a PSP Mini, along side Fieldrunners and a small hand full of other similar bite-sized titles. Recently making its way to the iPhone, Blast Off is nearly identical to its PSP counterpart, with the control scheme as the main differentiator.
In Blast Off, you control a tiny rocket ship blasting through space rescuing astronauts. Touching the screen tilts your ship in that direction and fires your rocket, usually sending you off that way. Your enemy in the game is gravity, and the game is over when you crash-- Numerous celestial bodies are scattered across each level, each which have a different effect on your ships trajectory.
As you blast through space, you have to keep an eye on your air and fuel gauges. Air serves as the timer for the levels, and fuel is consumed as you touch the screen to let off rocket burns. Once you get a feel for how the ship performs in space, it won't take long for you to sling shot around planets and use gravity to your advantage to really only need to fire your rocket for minor course changes.
Two different game modes are included, endless mode where you need to rescue as many astronauts as possible while picking up power ups to refuel and refill your air supply. Classic mode consists of 45 levels with multiple difficulties where players must collect as many astronauts on screen as possible then make their way to the warpgate without running out of air or fuel. Both game modes are a lot of fun, although I've found myself preferring endless mode.
Online scores and achievements are tracked via OpenFeint, and Halfbrick has even released the game's soundtrack as a free download on their site. If you've had fun with these kinds of gravity puzzle games in the past, Blast Off is really worth a look.
App Store Link: Blast Off, 99¢