Hi. I bought COD 4 way before the App Store came out. I just got my 2012 iMac without the optical drive so I need to find a way to play single player without the need of a CD. Unfortunately the only thing in my mind making this possible is that I might need to find one that comes with a torrent, however I want that to be a last resort. If anyone can tell me a way without the need of an external disk drive please tell me. Thanks.