the problem is that with the torrent you downloaded, its missing some of the files needed. Happens alot with torrents, if one bit in incorrect then that whole segment is unplayable. Since its campaign, then you cant move past that segment until its beaten. Thats the problem with torrents. As suggested before, buy the game. The only full proof way to play the game, which makes perfect sense.
Also, with new copyright protections being utilized by different companies, alot of times the data that you can copy, such as the game, doesnt allow for the full installed game to be cloned. Thus preventing pirates.
*edit* And if i remember right, cod ghosts is like a 41gb game. Maybe thats including multiplayer, but either way 11gb seems very small for the full game.