this is something I could see Gfree building.

Audiosurf synchronizes the environment, traffic patterns and scenery with the events in the current song. Each music file imported to the game by the user is first analyzed by the game engine, and an ASH file (containing the dynamics of the sounds and how the track and blocks are arranged) associated to the music is created and saved (typically around 30 kilobytes). This helps speed up the loading time of future replays of the same sound file. The game loads the environment from the ASH files, with the track's elevation, surface and layout reflected in the dynamics of the music being played. For example, if a player were to choose to play a very soft and mellow song, the track would be uphill, very slow, relaxing and rich in cool colors. If a player were to choose a very intense and loud song, the track would be downhill, sped up, thick with traffic and lit up with hot colors.