That was a really good game with a unique style ! I liked the art and the switching gameplay, it's really cool ! The changing music but with the same notes is very pleasant actually :)
I would just recommend to balance the difficulty a little bit, but this is not a big deal.
Unfortunately, i found a game-breaking bug for the puzzle part that enables you to go through walls, but that was funny actually xD
Overall this is a good work ! Keep it up !