Really nice game! I included it in my GBJam 5 compilation video series, if you'd like to take a look :)

The mechanic reminds me to old Game & Watch games, wich is not a bad thing. After a while playing without being hit any time I died intentionally because it started to feel a bit boring. I would tweak enemies velocity and add new AI patterns to keep the interest on during the game. Also I'd do something with sound, it is quite annoying.

With a bit of polishing feeling should become much better :).

Good core mechanics. I felt the enemies came way too fast though; a smoother difficulty curve and clearer differentiation of enemy health would help I think.