Lots of demos on the webste:
http://quest3d.com/index.php?id=15You'll notice very few (if any) have the level of complexity of Audiosurf though. Whilst they have much higher graphical fidelity, they're not processing music, moving a bazillion objects around and doing lots of other game-related stuff in there.
Dylan chose Quest3D because it's got a nice UI that allows you to rapidly prototype and make small games. Audiosurf just got too big I think. It's aimed more at doing demos for showing data, models and other prototyping things.
