Understanding Human Behavior (Score 1)

I think that one of the things which I would really like to see is the ability of the game to simulate a person's behavior. This would include such things as natural language processing and generation, emotion, goal-oriented behavior, etc. One of the most deficient part in games is that it is incredibly obvious that NPC's are NPC's. They are really just talking heads with a little dialogue to spout at the first sign that someone is paying attention. I guess what I'm really talking about is believable interaction between computer characters and the player. Of course, this is an "AI Complete" problem :-/.