Frooksville (a big city in the United States of Frookmerica) has been exposed to a disease that has turned most of the inhabitants into zombies. You're on team Zombo Buster, an elite special forces unit, and it's up to you to protect the peeps who are not zombies and to kill everyone else who has already turned.
You objective is to secure a building and keep the zombies out of it so that the remaining humans can get to it and out of harms way. This will involve blasting the brains out of the zombies before they reach the walls. This is challenging to begin and only gets harder as the game progresses. It's important that you upgrade and train yourself in the most efficient way. Go down the wrong path, and you may end up being brain food for the zombies.
Reloading is a pain in the butt to begin, so make sure you reload before a zombie is near the building wall!
Good luck with this. The peeps of the city need you to keep them alive.
***HUGE GAME, WILL TAKE A WHILE TO LOAD, PLEASE BE PATIENT***