I totally adore this concept, gotta ding you points for no sound tho.
Its especially odd because you have a volume slider button in your menu, witch I assume based on the 'Title Screen' is a prefab you up-cycled, (nothing wrong with that) but it was so close to having a nice coat of polish on top.
At first the darkness of the levels seemed a little oppressive, but it really emphasized the need to always be shooting and therefore introducing more chaos into the levels, turning every room into some kind of hellish nightclub dance floor.
I almost missed out on the purple orb heavy pistol type weapon, thinking it was the same as the base rifle, so a bright pink or purple coat of paint on that one would go a long way there.
Your shotgun gets a solid A for fun factor (I Gotta judge every FPS by its shotgun), and the health pickups seem generous enough for the typical amount of self harm your likely to inflict in a room.
I also am in love with the pixelated camera resolution, It really makes the otherwise dull stock assets pop.
Overall SUPER FUN GAME but, YOU REALLY NEED SOME MUSIC! Lots of great royalty free Drum & Base songs out there on Newgrounds just waiting to really make this game sing.