The zombies heisted the Stage Coach to try and fund a Western Zombie Apocalyptic Rebellion. You have to get back the money to stop the apocalypse.
Zombies are running everywhere, but they are now coming for you. When they pop through the door, shoot the zombies with guns, but don’t shoot the money. Once you get all the money back from each door, you advance to the next level and get one step closer to preventing the impending doom of an apocalypse.
Happy Zombie Hunting