Previously, I mentioned the name change of one of my more recent settings (wherein The Sundered Land became Some Dread Land). Now I would like to describe the folly of my earliest campaign worlds.
Murdundia (q.v.) was, I believe, my first original setting for Dungeons & Dragons. Unlike most role-playing fantasy settings, it reflected a monotheistic culture to make better use of paladins, clerics, demons, and devils. I think the name itself might have been inspired by "Mundania," the nonmagical land in the Xanth novels by Piers Anthony, but there the similiarity ended. "It's the world of... uh... Murdundia."
Cyclica was a setting dominated by a vast, circular megalopolis reminiscent of Constantinople and Lankhmar, but far more orderly. It was the only significant city in the known world, and the rest of civilization was feudal. I created the world of Cyclica as a setting for the adventures of a player character who was a saint, which was a class that appeared in DRAGON Magazine and was strictly intended for non-player characters. (Ludicrous, I know. We were junior high school students at the time, so that's our excuse.) "Cyclica" was meant to evoke the idea of a circular structure expanding gradually, but it always sounded contrived.
The World of Chickenhawk was my most detailed setting, a parody of a certain popular campaign world complete with sophomoric puns. I even ran an adventure at Gen Con set in Chickenhawk when I was a high school student. And I still have the world map and the adventure and the pregens! Chickenhawk is just, well, silly.