GTA: Anti Zombie Defense
The zombies are attacking and you are the only one left to defend the town. You need to get them all or they would eat the towns people. You won't get any back-ups since the people are scared and they are probably hiding. You are the only one with the gun and the training to fight the zombies. In this game, hordes of zombies would be coming from almost all places and you would need to defend yourself against their attack. Each kill would earn you money, which you can use to upgrade your character. It only means that your character would be tougher than before.