HOW DID YOU MAKE A GAME LIKE THIS IN 4 DAYS!!! This is awesome; as a person who loves music, this is great! The only piece of feedback that I can give you is the tutorial. People like me don't like reading a tonne, so maybe next time try to figure out a method of giving instructions to the player that does not involve a bunch of reading.
I would also really appreciate it if you where to rate my game :D