Eric-Jon Rssel Waugh has an excellent article on gamecareerguide.com on Animal Crossing, one of my favorite games. "Ambition and Compulsory Design in Animal Crossing" deals with games, goals, the motivations for play, and the platform context of a game. Well worth a read.
He calls Animal Crossing "the anti-game": there is no punishment for inaction, there is no real conflict, there is no major obstacle to collecting the widgets that, in most games, require serious effort to earn. This game should make everyone question their definition of what a game is, and what is necessary for a compelling game experience.
Why have I spent an embarrassing number of hours with Animal Crossing? Don't answer that. At least, I don't want to know the awful truth until after I finally get the lunar carpeting for my house, to go with all my other space macguffins.