That was fun! I really liked the atmosphere of constant tension when you don't have enough energy and can't see enemies anymore! The fact that you can't see your character in the light is, at first, quite frustrating, but after a while it became ok, but maybe you can add an indicator when you shoot in the light so you can see where you are or something, because I think it's a cool idea that can be improved...
The main problem I see is that it lacks of some kind of difficulty progression, it was kinda hard when I first started the game and I had to retry several time to have a correct score (Mainly because I'm bad at video-games :'( )
Overall, it's a great game for 48h, and I had a great time playing it so good job!