Overall a quite polished game.
At first I was concerned that spamming my spacebar would get me in trouble during work hours (my supervisor doesn't like it if I play games for some reason), but thankfully the option to continuously shoot with 'ctrl' avoided that.
I'd give it a 8/10 for working hours, due to it's addicting nature.
But a straight ten out of ten for playing it in your freetime!
Good job creating this (: