Yes... old-school Half-Life...
Anyway, it was given to me as a gift from a friend of mine who insists that I play the original before buying HL2. The Collection contains Half-Life: Game of the Year Edition, Opposing Force, Team Fortress Classic, Counter-Strike, and Blue Shift.
I downloaded Steam, created an account (not necessary for this, I know), and registered the CD key. Now, everything from the Platinum Collection is available to me... except Blue Shift.
If I enter in the CD key for Blue Shift, Steam tells me that I "already have active subscriptions to the game(s) associated with this CD key."
Does anyone know why?
: Ok, hmm... Apparently Blue Shift isn't available through Steam, because it's actually owned by Gearbox, who modified the original HL engine a bit. That makes sense, unfortunately.