You'd think that Portal 2's co-operative levels were designed specifically so that they could only be completed by two players working together. Turns out that's only half right.
While you do need two players to complete each room properly, YouTube user Gocnak quickly found that you only really need the other person to open the doors. All the other bits could be completed by just one person.
As you can see, in the video above. Those crying foul at all the floaty bits, Gocnak says "yes I did use noclip", but that it "was ONLY used to get through the doors, as, who would've thought, the doors don't open with one person."
