Portal 2: Peer Review includes an additional course for Portal 2 co-op campaign, dubbed "Art Therapy"; as well as Challenge Mode for both single-player or multiplayer campaign, where players can play specific levels and compete in friends/worldwide leader-board.

Portal 2: Peer Review includes an additional course for Portal 2 co-op campaign, dubbed "Art Therapy"; as well as Challenge Mode for both single-player or multiplayer campaign, where players can play specific levels and compete in friends/worldwide leader-board.