The Undead Mod

For a while now people have been playing games about the zombie uprising (or outbreak depending on the cause of the apocalypse), the best zombie game at the moment is probably Left 4 Dead 2 and there has been some attempts at making Zombie Apocalypse Simulations, but a love child of both would be Arma2's The Undead Mod.

Arma 2 is a very complicated military simulation game and The Undead Mod adds zombies. Why a large developer hasn't worked on something similar I don't know. There is clearly a market for this.