Nice game, very simple and easy to learn controls and the intro narration and tutorial are excellent.
I also like the sounds you used for the game everything blends really well and create a good immersive atmosphere. The visual cues were a nice touch.
I'm don't really play rythm games, so I can't really comment on the difficulty curve, but I think is ok for the jam timing constrains.
Also I think I used the same sound for the enemy attack in my game, I had to check twice I didn't leave my game open while I was playing your game.