Georgios Yannakakis sent me these links for the work he's been doing on adaptation mechanisms for increasing entertainment value. I caught his talk about this at the AI conference I keynoted at recently. The work is based on a neural network function that maps between various player metrics and the degree of fun that players report with the game (in this case, a simple Whack-a-Mole variant), and looks very promising.

• You can read his paper, "Real-time Adaptation of Augmented-Reality Games for Optimizing Player Satisfaction", here.
• You can see a video of the adaptive behaviour in action here.