DaRKSTaRxMeRC:

I can't really think of other FPS's that do anything like CoD did.

For the campaign and it's what-ifs. Turning Point: Fall of Liberty

Quite a large what-if, of course that's one game but there are other games with 'what-if' spins on historical or modern events.

I would give examples but I can't think right now due to classes.