Nice idea, but I had a few problems: first of all the mouse was moving too fast, when I pressed CTRL to crouch I lost my unique bullet, with Esc it shows the mouse but without a menu.
These are things you can fix this week without too many problems I think.
A thing a little more tricky to fix are the shadows, maybe instead of using the directional light trying to use more light points?
Apart this, the enemy was really creepy and I panicked when I saw him and I was without bullets, it was really fun to play