Offworld - The Far Reaches of Edutainment. Thanks Slashdot.
But I don't suppose that was the only reason. Games don't necessarily have to be fun to be engaging. Indeed "fun" seems like a trite expression in the face of some contemporary projects: games can provoke more than simple enjoyment. Look at the terrifying crypts of Stalker, or the strange sadness of Shadow of the Colossus. To realise that games ride on more than fun only takes a quick glance at the bigger picture.