U 2 Can Cheat 2 Win!!!
Not that it's really necessary, but on the second floor, if you make it to the south side of the level, basically straight across from the elevator, you can stand next to the black edge of the room and fire into the room. The recoil pushes you into the black area. Here, you can either wander into what I imagine is an infinite dark abyss or just walk around the OUTSIDE of the whole level and pick off most of the enemies while they can't get at you.
NOTE: if you stand close to the border while you are outside, you can shoot into the room (sometimes) but the bad guys can get at you as well. If you stand further away you can't shoot into the room, but when the baddies pursue you to the edge of the room, you can shoot them because part of their body hangs over into the void. They can't get at you there, obviously. Best tactic, hang out at the edge to lure them, then back up and destroy at your leisure. This doesn't work on any other level (I tried everywhere), and it only works on the left side of the bottom border on that level. Oh yah, I almost forgot. To get back in, just stand at the border (only in the same place you started), and shoot outwards, propelling yourself back in. You can't enter anywhere else either, unfortunately.
I liked it, it was fun. Usually I genuinely dislike top-down 3d games with diagonal boards and keyboard movement, but this one had smooth controls, and was pretty engaging, and challenging the first time around. Easy once you get the hang of it. Great sounds, great atmosphere with the lighting issue.
I would only offer one piece of constructive criticism. In the last level, with the little blurb where your dude says there's something BIG lurking around, there really should be a boss, or at least a new type of monster. In fact, it sounds like you were planning to do that but decided not to. Also, I gotta say I found no use for the secondary weapon. The pistol was fast enough, and I REALLY didn't wanna run out of ammo with an enemy bearing down. Good jorb. And thanks for that little cheatie bug. Please don't change it. I feel all smart 'n' stuff for finding it.