Love shmups, would have been nice to see more and with sound/music!
Some things I would change:
-Have the bullet sprites draw above the player but below the hitbox pixel (maybe at this res it's exaggerated though).
- Disabling the mouse input since it interferes with the keys when selecting character.
-Make the browser window bigger x2 or maybe add the full screen option
Oh and that background pixel art is top tier.
Even if you missed the deadline, well done :)