One of my least favorites was Ultima Ascension, or Ultima IX. It was, in a sense, a betrayal of the series, and everything Garriott had done before in it. The non-linearity, intensely personal, highly configurable character and parties of the old Ultima RPGs had been replaced by a one character, first person action game that was completely linear, with braindead AI, and completely focused on activities in puzzles. Never mind the bugs; I objected in advance to it being sold as part of the series, when it wouldn't appeal to any of the series audience. Garriott, ignoring this (as he always has) proceeded to invite destruction, and his old players howled back their anger at him.
Your turn.