The first Portal 2 downloadable content will launch on PlayStation 3, Xbox 360, PC, and Mac on October 4, Valve announced today.
‘Peer Review’ is a free update for Portal 2‘s co-op mode. Atlas and P-Body’s story continues “as you puzzle your way through a mysterious new co-op test track and once again match wits with GLaDOS.” It also features a single-player and co-op Challenge Mode, complete with leaderboards to compare scores with friends.