Okay, tried it again with the "F" key.
Here's my observations:
1) Still too dark. The torch effect is okay, but when you try to move whilst holding down "G", the light goes off and you're in the dark again. I'm sure this isn't your fault though and is a limitation of FPSC.
2) The invisible entity killed me twice before I could figure out what was going on. The only clue to its existence is the shadow circle below it, but you can't see that without pushing "G". When you're running around a dark room with only a knife, being attacked by something, but you don't know what, it's pretty involved to push the G key (plus it doesn't work if you're moving)
3) When I exited the game, it auto-restarted again. I had to exit using ctrl-alt-delete
4) The concept has good promise, but you need to "clue in" the player to hazards before they get to them. A torn newspaper on the floor warning of Invisible Dudes for example.
Keep at it, it was fun, but a bit annoying at the same time.