Swearing is a literary tool just like anything else. I think it's inclusion/exclusion would effect little to nothing of the content within the game. Also as I recall none of the Halo games used the "F" bomb. And if you're expecting graphic nudity/violence, I daresay you'll be disappointed. We here in the Bungie Community prefer "Carnage", which is like graphic violence, but with class. So to answer you: No. I don't think it NEEDS an M rating.