Really fun game! I liked the visuals, music and gameplay. It's amazing that you managed to add a boss fight in a jam game. Very cool!
A health bar, some penalty if you let an enemy pass and more kinds of powerups (like a shield) could make it even better if you're planning on working on it after the jam.
The game froze when I was playing the boss level. I tried reset but it was still frozen. But it's a jam game, stuff breaks. :)
Overall very well done!