Click here to get Portal for the PC, Absolutely free!
Promoting Steam being released on Mac, the Valve team have made portal, until the 24th ABSOLUTELY FREE!
Now everyone who's played this game realises what a beast it is, it's simply amazing, there is nothing quite like it. If you haven't played this game, I'd suggest making a Steam account (totally free here
Steam) and getting this once in a lifetime offer.
You will not regret getting this game, nor steam.
Free until the 24th so act soon.