Valve have today released the next instalment of free DLC for Portal 2. The new content includes a single player and co-op challenge mode, as well as a new series of tests that pit you against the spiteful A.I, GLaDOS.
For those who are still yet to experience the story of P-Body and Atlas, Portal 2 can be picked up for 50% off on Steam until Thursday, October 6th at 4pm PST.