Just curious as to why you guys think this game got an M rating. I have not played the game but I've seen some of the cutscenes and it doesn't look like there is much that would lead to an M rating.
Some strong language in there, it's been a long time since I played but I remember turning the volume down low during the cutscenes so that my parents couldn't hear downstairs.
Maybe it's because of the Louisa Philips side-story... More likely though, it has to do with a few rather offensive scenes, especially the Kronos stuff, and the general language.