I like the concept here. I'll note, however, that some way of reminding oneself of what the songs are would have been better; on the last level, I spent several minutes trying out different combinations in order to figure out how to change gravity again.
The speed of the physics versus my speed of inputing button combinations proved to be a bit of a roadblock, specifically for the last level. I think this game might have benefited from a slightly wider camera angle, as well as slower physics or larger gaps. That would enable the player to try to figure out a combination ahead of time, and have time to input it. (But maybe I'm just slow at putting in button combinations? I was never very good at fighting games.)