Valve has revealed that 1.5 million gamers have taken advantage of Portal being offered as a free download to promote Steam's launch on Apple Mac.

The publisher has also released some stats about the game, including that it's a fifth less likely to crash on Mac than Windows. It seems two thirds of Mac gamers are playing the game on a laptop and Mac game sales already account for 11 percent of Steam purchases.

You've still got time to grab the brilliant Portal for free, it's available for both PC and Mac until May 24th.