3 days, that means I completed Easy, Normal, Professional, Assignment Ada and Separate Ways.
I just didn't reach a five star rank yet everywhere in The Mercenaries, that's pretty hard, I just got five a few times, 4 isn't to hard, but with 5 I kinda give up...anyway, point of this isn't just to brag, the point is I completed these pretty fast, so what is your average time to complete the main game once?
Mine is +/- 8 hours, as it takes about 7 on Easy and 8:45 max on Pro.