The fourth mode in Block Fortress. Co-op mode allows you to play with up to four people at once through Gamecenter on ios, or a Google account on Android. The mode's characteristics are similar to quickstart. There is one build phase at the beginning of the game, after which the enemy attack will never end. The game is over when all players are dead or your barracks is destroyed. Players that die during the battle will automatically respawn after a little while. Players may enter the barracks to re-enter a building phase.