I really liked the idea that you were shooting for (ha) here and the mood that you have set. The implementation of the flashlight helped a lot with this.
Despite running around the map a couple of times, I could not figure out how to find a gun or other weapon. I did find a beer bottle or a knife or something in a small building with black walls but could not figure out how to use that to my advantage. When I start the game, I think it would've helped me a lot to be spawned in a building (so that you can force the player to experience specific things in an organic way) with a gun in one of the rooms. That way, I am able to get to the core mechanic of the game (killing zombies) as fast as possible.
About the controls: I would say that while pressing W and S to go forward and backward relative to the player's rotation works well in a 3D FPS game, it was a bit jarring to have those controls in a top down. Personally, I think I would have preferred the ability to walk up, down, left, right, and then spin around freely without it messing up the direction I was going.