Did you guys make a song in 9 days? That's crazy! Super impressed regardless; the game is incredibly polished. The art style and color choice work well! Very pop and electric core.
I think I only have one piece of feedback that comes to mind. I noticed that you could mash the note buttons and completely remove the need to time your presses to the beat. Not sure if that's a good thing or not, but maybe adding a feature that punishes the player for playing a note super early could be interesting.
Either way, cool stuff! If you continue to work on it, keep it up!