Portal is FREE.
If, like me, you already have portal for PC you can get it for your other Steam accounts and then have 'Portal Races' with your friends to see who can complete the game the fastest.
I now have 3 copies for PC and one for my 360 via my Orange Box DVD.
P.S. if you ever wanted World of Goo for one cent now's your chance with the Humble Indie Bundle.
If, like me, you already have portal for PC you can get it for your other Steam accounts and then have 'Portal Races' with your friends to see who can complete the game the fastest.
I now have 3 copies for PC and one for my 360 via my Orange Box DVD.
P.S. if you ever wanted World of Goo for one cent now's your chance with the Humble Indie Bundle.