south park the stick of truth pre purchase g2a pre purchase rewards

yeah. but its a SP only game, they are not all that important anyway.
However, sometimes they do, if they do though, they will advertise the shit out of it, so you would know.

If you got it from another site, that site might have their own pre-order bonuses separate from Steam. For example if you got Thief from another site you would not get TF2 items.