Another emotional experience! The graphics are really trippy!
The music sounds like it was compressed, plus the gain might be too high cause in some of the heavier bass parts it starts clipping. Also, I think there's a performance leak somewhere cause the game goes from smooth to choppy in half a minute if you linger on the same level for too long. Maybe objects being spawned aren't being deleted after use?
Great game overall! I'd add an epilepsy warning for sure. Also, this would have been a good game to test newgrounds medal api, unlocking a medal for a particular note or something. Just a suggestion :D