I used to be a professional games programmer and designer and I'm very interested in fun. There are a couple of good books on the subject: A theory of fun and Rules of play. As a designer I spent many months analyzing sales figures for both computer games and other conventional toys. The patterns within them are quite interesting: for example child's toys pass from amorphous learning tools (bright objects and blobby humanoids), through mimicking parents (accurate baby dolls), to mimicking older children (sexualised dolls and makeup). My ultimate conclusions were that fun takes many forms whose source can be ultimately reduced to what motivates us. In effect, fun things are mental hacks of our intrinsic motivations. I gave a couple of talks on my take on what these motivations are. I'd be happy to repeat this material here (or upload and link to the videos if people prefer).
I found Rules of Play to be little more than a collection of unnecessary (if clearly-defined) jargon and glittering generalities about how wonderful and legitimate games are. Possibly an alien or non-neurotypical who had no idea what a game was might gather some idea of games from reading the book, but it certainly didn't do anything for me to help me understand games better than I already do from playing them. Did I miss something?
This thread is for the discussion of Less Wrong topics that have not appeared in recent posts. If a discussion gets unwieldy, celebrate by turning it into a top-level post.