Video: a compelling lecture about fun - http://vimeo.com/74943170
Quotation: "Fun is related to structure, not to affect. So you can't 'add fun' to something, no more than you can cover broccoli with chocolate... You can only craft structures that might, sort of, excrete fun under certain conditions. And there's this paradox... Play is an activity of freedom and openness and possibility, but it's one that arises from limiting our freedoms rather than expanding them."
(27m01s, quotation from 17m47s; see also MacIntyre)