I understand that many CoD players have returned to Black Ops 2. I think Black Ops 1 was the last CoD I played for any length of time. I own Black Ops 2 but put more hours in to the last MoH than I did in to BO2!
So check this out... I downloaded CoD Ghosts during the free weekend period. After I had it installed I tried to play it, but it listed the game in the "Other games" category and wouldn't let me try the free weekend trial.
The only option I got during the free weekend was to purchase the game. Don't get me wrong here. I probably wouldn't have purchased the game, but a few other people I know of had the same problem when trying to play the free weekend trial.
Fail by Steam? Probably, but its just another example of how much CoD products dating from MW2 - present have sucked for support on the PC.