Over on his personal blog Michael Russell, the former quality manager at Ritual, has a nice
post up about how to manipulate ESRB ratings. There really is not difference in how realistic the violence in the game is but rather if the violence has consequences or not. GTA gets the M rating because the police will chase you around for a little bit while
Manhunt 2 gets the AO rating because the violence was encouraged and there were no real repercussions for the violence.
I can see why the ESRB would have this rule. I mean if there were no consequences in video games we'd all be out shooting up the place, running down people in the city, and all kind of uncivilized behavior. If the AO rating wasn't a retail death sentence for games this really wouldn't be that big of a deal but given the ramifications of the AO on a box it is a bit frustrating.