Fun: Zombie Games

Other battling the undead hordes in Urban Dead (which I really enjoy) you might want to try playing Zombies 4 and Winter Zombies. They're simple java-based shooters where you try to contain and confront a zombie outbreak on a series of maps. It's good fun. Winter Zombies seems to be a bit more difficult than Zombies 4 so you might want to start with Zombies 4 first.