Loved the art style of this game and I thought that the gameplay was fairly engaging throughout. I liked the idea of getting new weapons and when I unlocked the lightning guitar, that was a really cool moment. You also had a very polished presentation of the game and the UI was very intuitive. Something that I would love to see more of is the types of weapons. I loved the creativity of using instruments as weapons but it may be cool if the weapons had different effects - like if the drum was particularly good at clearing out all the obstacles in the room. I also felt like the enemy AI was very easy to avoid by running in circles around the room. An idea that I just had about potentially fixing this issue without too much extra coding (because I know how hard coding AIs can be) is a stationary laser tower that fires beams at you. I think this may provide the added challenge because even if you use a simple look_at() function to shoot the beam and then have a quick timer before firing, the beam would naturally be more accurate when the player is closer to the tower than when further away. Just some quick ideas though.
Cheers and good luck in the game jam!