Highly nonstandardfantasy game created by M.A.R. Barker. First officially published in 1975.The setting is Tekumel, home of the Tsolyani Empire and several other civilizations, both human and not.
This work contains examples of:
After the End: multiple ends actually, including the "Latter Times" (sometime after the "Time of Darkness" when Tekumel dropped into a pocket dimension nearly 50,000 years ago), to the more current (5,000 or so years ago) collapse of the worldwide empire of Engsvan Hla Ganga.
Aliens Never Invented The Wheel: Actually, humans forget about the wheel for the most part, in their decline from technological civilization to agrarian culture. They have the wheel, but they have nothing like a horse for wheeled vehicles, and lost the idea for the bicycle.
Apocalypse How: Tekumel has survived unorthodox planetary destruction (dropped into a pocket dimension) and multiple societal collapses.
Bizarre Alien Sexes: All over the place. Shén, Tinalíya, and Pygmy Folk have three genders, while the Hlüss and Ssú have hive like arrangements. The Ahoggyá are rumored to have eight genders, and nobody knows how they reproduce.
Blue and Orange Morality: The aliens have, well, alien morality systems, and the humans have various group-oriented moral systems that are not at all modern Western.
Con Lang: One of the first, and most developed. Barker developed Tekumel for basically the same reasons Tolkien did: to build a language around. The results (there are several) are a combination of conversion and original.
Eternal English: Completely averted. English is the dead language of a long dead culture.
Language Drift: The setting has changed over tens of thousands of years, and drift applies.
Horse of a Different Color: Averted, as there are no riding animals. There are draft animals, the chlen, and small pack animals, the hma, though.
Lost Technology: Tekumel is riddled with devices from the Time of Darkness and the Latter Times that are just barely comprehensible to modern Tekumelani, including an underground antigravity car system.
Mayincatec: The whole setting is a blend of Mesoamerican, Indian, Mogul, Chinese, and certain African cultures.
Order Versus Chaos: Or, in this case, Stability and Change, with attendant parallel pantheons, and not necessarily at odds.
Organic Technology: Of a sort. Metal is rare, but the hide of a chlen can be stripped off the living animal (which sheds it), chemically processed, and shaped into a leather as hard as bronze, including armor and hand weapons.
Our Monsters Are Different: Some of the creatures on Tekumel are Expies of standard fantasy role-play monsters, but they are distinctly different from your average D&D hack-ups.
Our Monsters Are Weird: The monsters and other creatures are a hash chili of Earth creatures, genetically engineered Earth animals, alien creatures, native species, and possibly extradimensional creatures, all to some extent evolved over tens of thousands of years of history and adaptation. Some are friendly, some are neutral, some are hostile, some are animals, others intelligent, and most are exotic. No elves, dwarves, gnomes, goblins, trolls, or other standard Western fantasy creatures.
Pocket Dimension: The whole solar system dropped into a pocket dimension eons ago.