The SFX are quite nice they really work well to convey the feel, and the little screen shake works well too!
The sprites could use a little work though, they don't seem to have much of a style. They're quite functional, but not too pretty.
I like the overall idea of the game, and having to balance between having vision and having ammo is good, but I feel like 5 minutes might be too long, and a timer there to tell you how long is left would be very nice.