While playing this particular defense game, you are in a situation where a big part of the city has been secured while the infection was spreading in the city. However, there is still a big area infected. Infected area has been bordered with walls that zombies cannot pass. So all zombies are running through the only road that has not been closed by walls yet. Infection must not spread out from the city. Defend the road with your team. Do not let any zombie pass the road. Use the mouse to aim and shoot. Press space bar to reload your weapon. Press Z to call airplane but mind you that you can use it only once in a level. Do not let any zombie pass the road.