Valve’s Portal free until 20 September

Do you own a PC? Do you somehow not own Portal yet? Well, this is chance number 52 to get it for free.
I think Valve has given away PC copies of Portal at least twice before. But that’s ok, because Portal is a fine game. It’s about four hours long and you can show it to people who think videogames are all about decapitating prostitutes or whatever.
Why the freeness? Because Valve is engaging in some sort of learning initiative using the game (and its sequel).
Follow the source link to read more about that, and for a link to freebie Portal (until 20 September, that is).