Encyclopedia of Xanth

Not a numbered Xanth novel but a branching Crossroads Adventure gamebook, written by Jody Lynn Nye in Piers Anthony's world, where the reader's own choices determine which creature, spell, or corner of Xanth gets explored next. It trades the series' usual single narrator for a hands-on tour of the setting, aimed at fans who want to poke around Xanth's geography themselves rather than follow one hero's quest.