A rare case where the generic nature of zombie horror actually benefits the game. The premise of it is very simple - you run through a level and kill zombies along the way. The thing that makes it special is the earnestly silly tone of it which really shines through the simple premise. The exaggerated design of the special zombies. The fact that the cow one yells "moo". The way the characters call out items you in almost childish excitement. It's something similar to what Team Fortress 2 does. All of this character makes it feel like it is much more than its very simple component parts.