You want a mature Kinect title? Sega's got your mature Kinect title in Rise of Nightmares, featured in this E3 trailer that looks like one of today's edgier horror films threw up.
When I first saw Microsoft's Kinect in action, my immediate thought was "Finally I can play a game in which I truly feel like a psycho killer is about to pop my eye like an overripe cherry". I have very strange thoughts sometimes.
The trailer doesn't actually show us much of the game. I guess its much easier to get someone to look cheery playing Kinect Sports than it is getting them to sit in a chair and piss themselves.