Portal 2: Peer Review was developed for Portal 2 and was released on October 4, 2011. The DLC was launched across all platforms (Steam, Xbox Live, PSN) free of charge.
It continues the story of ATLAS and P-Body as they assist GLaDOS in finding a mysterious intruder in the facility, and adds a challenge mode for both singleplayer and co-op maps, allowing a player to race certain maps, trying to place the least amount of portals in the shortest amount of time, as well as compare their scores with other users.
