togelius writes "What makes games fun? Some (e.g. Raph Koster) claim that fun is learning — fun games are those which are easy to learn, but hard to master, with a long and smooth learning curve. I think we can create fun game rules automatically through measuring their learnability. In a recent experiment, we do this using evolutionary computation, and create some simple Pacman-like new games completely without human intervention! Perhaps this has a future in game design? The academic paper (PDF) is available as well."