I was down at Value Village and bought a used CD of Half-Life 1 GOTY. I try activating the CD key on Steam, and it says the CD key has already been activated. Would just installing from the CD work instead of Steam? I believe HL1 was before Steam era, so it shouldn't affect installing the CD. I remember other games from before online registration they'd work even if used with the CD key. Does HL1 require Steam now, or can I still install without Steam?