Steam's Portal 2
now supports split-screen and Big Picture mode, meaning PC and Mac players can enjoy inter-spatial robo-cooperation on their TV sets. Valve's patch notes
say split-screen co-op is accessed by pressing X on the second controller in the first co-op menu.
The patch also fixed a couple of minor errors, including not being able to exit the Robot Enrichment or Create Test Chambers menus with the controller. We at the Joystiq Enrichment Center would like to remind you that any inability to exit Joystiq is perfectly regular, and your enforced presence on our website is most