Wonderful job! I like the sensations portrayed by this game, the gloomy colors in conjunction with the scenery, the shooting and jumping sounds that reverberate and complement the music...
One thing I'd suggest is that despite the player having lights, sometimes I find hard to climb the platforms because it seems way too dark. There are some platforms that when I fall beneath them, I remain trapped to that direction and have to go around to the opposite direction which can be sometimes frustating.
Other than that, good work!