The gameplay is super tight, the bullet travel is smooth and the enemies are well designed with their health and speed. Everything seems really balanced.
Suggestions:
-At the very beginning top left (and a few other places) I could clip through the walls. Not game-breaking, but I would fix the hitboxes in those areas because I was running through the wall.
-Tutorial/ instructions at the start to explain mechanics better. I died so quickly right off the bat for seemingly no reason until I could figure it out.
Awesome game, keep up the great work!