Perhaps to celebrate all the newcomers onto Steam thanks to the new version available for Mac, Valve is making the best first person puzzler ever completely free of charge.
Yes, that's right, from now until May 24, Portal is available on Steam for absolutely nothing more than just a few mouse click.
Regardless whether you're playing on a Mac or PC, there's no excuse not to own Portal – especially since you need to get caught up before the sequel hits later this year.