RPGCodex provides us with a retrospective of the early 90's SSI AD&D title, set in the Dark Sun campaign setting, Dark Sun: Shattered Lands. Note that when I say retrospective, I mean a spoiler-laden walkthrough.
The world of Dark Sun is called Athas. It's a desert world where the conditions are harsh, water is scarce, resources like metal are almost depleted and only the fittest, strongest and smartest can survive. That's the reason there is no level-less commoner class in the Dark Sun setting, odds are even your cleaning lady is a level 3 fighter with a strength of 18/00. You're already something special if you can survive in this environment at all, as the weak have long been weeded out. It's basically the D&D version of a post-apocalyptic wasteland, except the apocalypse has never really stopped. Due to the depleted resources most weapons and armor are crafted from bones, stone, obsidian, wood, and leather, which makes metal weapons/armor, let alone enchanted weaponry, very, very rare. Shattered Lands might not be the easiest game to pick up for modern gamers, but it is absolutely one of my personal favorite cRPGs of all time. Worth a spin if you have the time.
The races inhabiting Athas are mostly your typical D&D races like humans, elves, half-elves, dwarves, muls (half-dwarves) and halflings but also more exotic races like half-giants or thri-kreen (intelligent insectoids) make their appearance. Of course they're not just what their names seem to indicate. Elves, for example, are not of the tree-hugger variety; they are mostly thieves, marauders or even slavers, plus as every creature on Athas they're taller, bigger, stronger and more durable than their counterparts from other D&D settings. Halflings are mostly known as a savage tribal people, rampant cannibals attacking and consuming everyone who dares to enter their territories. Remember those halflings from the planar sphere in Athkatla (Baldur's Gate II) who tried to eat you? Yes, that's them.
The most significant sparks of civilization are the city states, like in ancient Mesopotamia, each ruled by a sorcerer-king who is worshiped as a god. The city of Draj and its surroundings are where the game takes place; this city is ruled by the sorcerer king Tectuktitlay, and the whole region including the slave villages like Teaquetzl is inspired by the Aztecs, as you've probably figured out by the names used. Another one of these city-states is the city of Tyr, the stage for the second game, Wake of the Ravager. It's the only city free of the malevolent rule of a sorcerer-king because its sorcerer-king Karak has been slain on the brink of ascension by a gladiator. The sorcerer-kings of Athas are powerful defilers and most likely dragons in disguise.