BaK was great! I must have played it some ten times or so, even though it is semi-linear (that is, you have a mission in each chapter, but you're allowed to loiter pretty much over the map). It's got over 100 riddles that a DM can try the players with (you can find all of them, with answers, at the sites devoted to the game).
Did somebody attempt a conversion of Feist's works to d20 rules?