That ideal body that I'd like tohave in my game would support everything that KittyKunt described. That's what would pose the most difficulty imo - creating an incredibly realistic body would be pretty computationally intensive. I'm talking about bloodflow simulation, nervous system bodypart control, needs simulation and... perhaps procedurally generated animations to make for the myriad ways a body could be mutilated.

That, paired with a good AI that simulates a realistic human daily routine for everyday life would probably make the most fun man hunting simulator.