I'd be wary about preordering an unannounced game for Steam except through Steam itself. I wouldn't even use vendors I know to be reputable, such as GreenManGaming.
Don't get me wrong, we
already knew it was probably to PC and PS4 (or at the very least had been worked on and abandoned), but without verification from either Rockstar/Take-Two or Valve, I'm not going to assume it's necessarily coming to Steam and not Origin or something.
