I liked the combat, but it felt really bad when you would get hit and you didn't even know why, it's nice to have a sound, flash or vignette effect when you get hit so the player doesn't feel robbed when he suddenly finds out he is on 5%
The audio was okay, but i wish some sounds (like the player shooting) where randomized so they didn't feel as static. Also the repeating song got a little annoying after some time.
The art was pretty nice and consistent throughout the whole game and had a nice feel.
The enemies had cool patterns and the boss idea was cool, i just wish there was some more communication to the player about getting hit, getting shot and stuff like that.
Overall very solid submission, great job!