Portal available for free on PC and Mac

Steam has released Portal for free for the PC and Mac. The game which would generally cost $10 is regarded by many as one of the best games of all time. This announcement comes from Steam in an attempt to boost sales of the sequel - Portal 2 which is currently selling at $29.99.

Portal is a single-player first person puzzle-platform video game developed by Valve Corporation.

You can download Portal for PC and Mac here.