I loved Faxanadu as a kid. I found out a few years ago that it was related to another NES game I really liked, Legacy of the Wizard (Dragon Slayer IV: Drasle Family in Japan). They were both part of the Dragon Slayer series in Japan. Though the games play nothing alike, they do have some elements that time them together, such as a number spell-names and weapon names (at least the Dragonslayer weapons) in common.