Basically. Going to use ZAPT to make it more interesting. I think this is different than other zombie games because it's actually dark. The lights are either quite dim, or barely anything, so it make it more fun because you don't know what is going to jump out at you.
Just a thought, I think you should add some triggers or switches that players can step on without noticing..such as let me run a sample scenario.
Player 1 and player 2 walk into an empty ally.
Player 1 doesn't know but he just touched an invisible switch that just deleted a wall of a building.
The wall blocking a zombie is deleted behind the players.
The players stop to see if any zombies are around, without looking in back of them, because they just came from that way.
Player 2 dies.
Player 1 notices and quickly assesses the situation and starts firing at the zombie.
Zombie dies.
When zombie dies more walls open up, releasing more zombies.
Player 1 dies.