Cooperative player mode or co-op for short is when several players play together to aid each other. Ratchet: Deadlocked was the first game to have co-operative player mode which allowed two players to work together to complete the game in splitscreen. Ratchet & Clank Size Matters also included a co-operative mode in the Playstation 2 version of the game, but was only in the Multiplayer maps of the game and not the campaign unlike Deadlocked. Ratchet & Clank: All 4 One included a co-operative mode allowing up to four players to simultaneously play the game and work together to complete the game and Ratchet & Clank: Full Frontal Assault will use a co-op system similar to All 4 One as well.