My thoughts... What is the function games? What is the function of play? What is fun?
Play is an abstraction of the real world. It is a containable subset with creative bounds. Rules create games and system thinking out of play's abstraction. Computer games offer variation, additional complexity, and deeper simulation. It is a primary mechanism for developing meta-cognitive thinking. Why is play fun? Because fun is a reward; the brain is wired to reward things that are good for it. Play is particularly fun for kids, because it is particularly important for kids.
There is another bounded type of play where there are fixed constraints inherent to the system, but not rules outside of those. Those are simulations, and they help build the metacognitive skills that are useful for design and creative problem solving. Minecraft falls into this area and has much support for system and thinking and cooperative problem solving.
Then there is a fuzzy line where play and games slip past being a means and become an end.
