The gameplay... Looks just a bit bland at this point.
There aren't very zombies from what I can see, and the constant darkness is rather annoying. Most of the time I couldn't see what you were shooting at. If you want your game to be dark, I would at least include a flashlight.
Neither the sound effects nor the zombies were really creepy. The chuckle sounded like something you'd here in an insane asylum. Last time I checked, zombies grunt, moan, scream, and growl, but chuckle? That just seems a bit... Silly. Also, the animation didn't seem very zombie-like. They seemed to walk just like normal people. They didn't shamble or even walk at a slower pace than normal.
The rest of the sound effects I recognized from other games like Half-Life and didn't fit the theme very well. You should really record/find/buy other sound effects for your game.
There were some things I liked about the game, however, like requiring the player to "use" objects like doors, weapons, and ammo. I can imagine the player being chased down a hallway by lots of zombies, only to run into a door, fumble with the latch, and die. I also liked the fact that zombies would strafe to avoid your bullets and such. The models were also pretty good, and the textures were good, although not spectacular... Maybe with some normal/bump mapping, they would look even more realistic.
All in all, I can see you've spent time on this. Keep it up, and remember to give the player a flashlight...