Just wanted to revive this thread to mention an MMO (World of Warcraft type game) that is in development called Revival that may have some pretty interesting features. This is taken from their latest dev blog:
"With that being said, you will see a lot of features in the game that you don’t usually see in a game. Some of these are things most developers won’t touch with a ten foot pole because they are scared of the backlash. These things range from taking a shit, pissing, having sex... Let’s talk about sex. For starters, yes, you can have graphic sex in Revival... Sex is a cooperative mini-game. You do not control anything other than a simple mini-game during sex. In the background of the mini-game, the animations run for the sexual experience. The mini-game goes on as long as you can ‘maintain’."
I was interested in this game before this blog post came out but I am glad to see they are not shying away from an M or harsher rating.