Google it if you don't know. I can't launch any games from steam. Halp! Just a white screen with sound which freezes and then crashes.
Don't get discouraged if no one is posting, they just don't want to post saying 'Don't Know'... Which is basically what I am doing right here... I don't use Steam, I've got myself a crappy Macintosh that can't even read discs let alone download games from the internet!