Well, since I'm posting this in another thread anyway…

Spoiler: random post apocalyptic D&D
Show
Minecraft logic for topography. And variable-length days / seasons. And reproduction? That's for higher lifeforms only - plants and animals just spontaneously appear. (Arcane) Magic? It's not "chance" or "genetics", it's diet - and (whether they realize it or not) Dragons are the only ones who can sense which bits of matter have become infected with midichlorians (although having draconic ancestry certainly helps your odds of eating dirt as a kid and becoming a Sorcerer in the process).

I might well try to use both the "god of <race>” and "god of Wizards" portfolios to remove "Wizard" is a class, and create a new race of "Querti", beings with inherent learned magical potential, and the ability and inclination to research new spells. Their "Sorcerers" lack the "spells known" limit; or, rather, can break that limit through spell research.

Druids, as defenders of the new "Nature", might look at higher races (and themselves) with disgust, calling them "free births", and encouraging a quixotic, Glaconda-like return to the more natural spontaneous spawning.

Elves should do what elves do, and evolve new variants, adapted to the intervening wastes. "Wastes elves", ethereal elves, maybe even sea elves seem plausible.

Undead… not sure where to go here. Definitely want the return of Baelnorm. Not sure how to go about that. Maybe make a world where "undead" are the "good guys", bringing life to the world with their very presence. Yeah, that's it! Undead are powered by Life, they're the heroes who brought the world back from desolation. They explain how life just spontaneously generates. Kill off too many, and the world goes back to being a wasteland. Maybe it is in some places, because of the strength of the local Clergy of Pelor. Places rife with undead become rich with life - overgrown jungles, forests with powerful nature spirits, etc.

It would be nice to change the 4 elements while we're at it… I'll give it some thought.

Druids build great "Stonehenge"-style structures; the power of which, secretly, is to control the various "biomes" - life here is "desert"; life next door is "arctic"; next to that is "forest", etc. The code for these is in the unreadable, otherwise unlearnable Druidic language.

These Stonehenge control structures dictate *which* plants and animals will spontaneously appear, what the temperature will be like, etc. Actually building or changing them is an Epic-level ability.

Geometers (not sure what they are, mechanically - perhaps Warlocks or Artificers or Factotems, or perhaps something entirely new) have learned to hack the system with (what they don't realize is) pidgin-Druidic, creating magical sigils that will cause a single plant to spontaneously grow in a particular area.

Thus, in some parts of the world, "commoners" are replaced with Geometers, and nature-oriented Geometers, known as "farmers", practice the heretical arts of controlling nature through "crop circles".

-----

Most races of "Monsters" are the result of flaws in the system.

For example, if a cow attempts to spawn at the edge of a zone, and the adjacent zone does not recognize cattle as valid, a gorgon might be formed instead. If a cow tries to spawn in an area occupied by a human, you might get a Minotaur.

Thus, the world can be filled with Wondrous one-offs, like milkweed trees that give actual milk.

Such defects are far more common where the system is being hacked (such as near crop circles). Thus, because cities normally require agriculture, in a perversion of expectations, city zones are actually among the most dangerous in the world.

who said anyone actually knows that undead work that way (other than *maybe* the gods, who probably aren't telling)? There's still lots of (ie, the exact same) prejudice against undead in this world (as projected) as exists in any other world. Everything is understood backwards ("undead like to congregate in high life areas", "witches who own black cats cause the plague", "a good rain tends to cool things down", "this area needs the protection of the city because of the terrible monsters here", etc).