You are trapped in a cabin in the middle of nowhere! Hordes of zombies are closing in from everywhere! Twenty gruelling waves of undead must be repelled. All you have is your one and only friend: Your trusted gun. Having the capacity to upgrade is a truly remarkable quality of your gun. But... alas! This comes at a cost. You have to kill zombies! The more you kill the more upgrades will you be able to make. Got it? Go for it!