Momentum is a blast from the past. It is based on those old school games from the days of the Commodore 64.
You control a basic triangular shaped ship like the ship from asteroids. In this game though, you have to deal with landscape and gravity.
If you ever played Thrust on the Commodore 64, then you pretty much know what to expect. Momentum is much the same as this retro classic but with control via your iPhone rather than by a keyboard.
A word of warning. This game is hard.