I have purchased COD4 Modern Warfare YEARS ago. While I have played it in the past, I have now installed on a new PC and I'd like to add it to my Steam since it is a game found in Steam as well.The CD KEY from this retail case, doesn't seem to work in Steam or Origin.
Is there a way I can add this to my Steam Library? And I don't mean via "non-steam game"... I would like Steam to know that I have a ligit copy and it must be part of my account.