Up to four players must survive against endless waves of attacking zombies, earning points from killing or damaging zombies and repairing barriers. These points can be used to purchase weapons and, in Exo Zombies, Exo Upgrades in the process, or unlock new areas and activate other special objects. Zombies enter the player-accessible area of the map through a variety of entrances, from rooftops to doorways. There is no limit to the number of rounds; the game will end when all players have been incapacitated or killed by the Zombies, or if the player completes the alternate ending of Game Over, Man! on Outbreak or Flotsam & Jetsam on Carrier. Zombies become stronger, faster and in higher numbers upon the completion of each round, forcing players to make tactical decisions about point spending and progressing through the map. On occasion, zombies will drop power-ups upon their death, making the round easier.