"Unplayable" is a word that gets bandied about in discussions of games, usually as hyperbole for "I don't like this game." I've definitely encountered games that I just didn't have it in me to learn. I never made it out of character creation in Gygax's Dangerous Journeys, for example.
But I think there is only one game I've read that I really considered unplayable: Nobilis, 3rd edition. I read it cover-to-cover and ended up having no idea how you were actually supposed to use it.
I don't want to offend any fans of it, but...I literally could not find the game in there. Note: I'm not saying that everyone would have this problem; I am saying I tried and could not make heads or tails of it at all.
