Valve today announced that the free DLC update for its bestselling game franchise Portal 2 will be rolled out across all regions starting October 4th. The free DLC, titled “Portal 2: Peer Review”, is available to all owners of Portal 2 for download on PS3 and Xbox 360, and will be automatically downloaded via Steam on PC and Mac.

In “Peer Review”, you and a friend will continue the story of loyal bots P-Body and Atlas as you puzzle your way through a mysterious new co-op test track and once again match wits with GLaDOS. The DLC also features a single player and co-op Challenge Mode, and leaderboards to compare Challenge Mode scores with friends and the Portal community.