Fri, Sep 16, 2011 | 12:44 BST
Portal goes free on Steam until Tuesday – get it now
Valve’s made the original Portal free to get from Steam on PC and Mac, but only from now until Tuesday. If you don’t already have the game, get to it here. You’d be very, very silly if you don’t, although that begs an entirely different question: why don’t you have it in the first place?