Eric Zimmerman spoke eloquently on games as the second day keynote at DevLearn. In it, he talked about how systems thinking was important, how games are systems of rules and consequently develop systems thinking. He talked about how our play brings meaning to the rules, and that creating spaces of possible outcomes allow us to explore.
He ended up advocating that we design for possibilities of unexpected outcomes to create meaning for our learners. Cammy Bean has blogged the presentation too.

At core was an alignment between what makes effective learning practice, and what makes engaging experiences.   Looking across educational theories, repeated elements emerge. Similarly with experience design.   It turns that they perfectly align.   If you recognize that, and can execute against it, your learning will be greater than the sum of the parts, and will both seriously engage and truly educate.   Learning can, and should, be hard fun!