Arborea
After the Apocalypse, the reversion of the gods to unconscious forms of life or hero-tombs when their minds were sealed outside the fractal compression of time-at-the-end-of-time in which we all live, the breaking of the old Alignment System, and the loss of many other anchors to the planes' long-standing identities allowed for an unprecedented degree of mutation directed by the will of their many inhabitants. In the case of the Chaotic Good plane, their understanding of joy, of pleasure, led to The Genre Shift, in which the themes of the entire plane entered a maturity rating above that of the campaign itself, causing its people's stories to be sealed off from the rest of the cosmos not by spatial folds or destruction, but by its XXX rating and the good manners of the DM. The fates of those who must still live there may not be for the worse, but like the top two layers of the Five Remaining Heavens, they serve as an example of a way worlds can be "lost" to the rest of the Wheel.
Never mind the magazines whose details are never described which are hidden under many people's beds, where they were photographed or printed or shipped from, or why the MoTrak railway to that plane appears to carry traffic; It's LOST. STOP LOOKING.
