GTA: Bloody Sunset
At night the zombies arise from the grave to feast upon the living. But, that is long story that has not been come true since you came to the town. You would often get rid of the zombies before they can even set foot to the town. The zombies would come attacking and you need to defend the town against them. Each kill would earn you money and you can use the money to buy better weapon. You can also upgrade your character base on what you want. The game gets more challenging as you make some progress.