Great submission. I like the main gun mechanics, the most satisfying part was grouping enemies together and then killing them all in one shot. The camera shake is a really nice touch, those little details really add to the aesthetic of the game.
My 2 cents if want to continue working on this: Maybe make it a tiny bit more forgiving like dying from 2 hits instead of 1. Also, I don't really use the machine gun that much, a whacky alternative could be something like a bomb or a grenade that you can also pick up by killing minions.
Anyway, I played like 3 extra games while writing this comment, so good job!