The best way I can describe Supersonic is that it is a mix of Audiosurf and the special stages in Sonic The Hedgehog 2 when trying to collect the Chaos Emeralds. You hurtle along a tunnel in the first person perspective and tilt the iPhone left or right to move in the desired direction in order to collect gems and avoid bombs and beams blocking your path. Where Audiosurf comes into it is you are able to select any music from your iPod and the game will generate a track for you to race through while the music is blaring out. All you need to do is plug your headphones in, turn up the volume and embark on a new way to engage with the music you love.
The only downside to Supersonic is that it is a freemium game. While it is free to download, you only get one level and to get anymore you need to purchase a level pack. The way around this though is by importing your own music, thereby adding more levels by using your in game credits. Although this is a downside it is ultimately not a bad thing as the best way to play Supersonic is with your own music and procedurally generated tracks.
Get Supersonic here.