World Introduction: "D&D Industrial"
This project started while I was taking a World War One history class — I learned a lot about how the Industrial Revolution changed the face of warfare, and as a lifelong D&D nerd, I immediately started asking myself "if a D&D world's Industrial Revolution was based on magical 1400s technology instead of on non-magical 1800s technology, how would the WWI equivalent have been different?"
The most important principles that I originally started with were
The minotaurs started out the least technologically advanced, but the most industrially efficient with the limited technology they did have. One of the more advanced nations tried to rebuild minotaur society in their own image by teaching the most advanced minotaur archmages their own most advanced knowledge in exchange for recruiting them as local colonial governors — instead, the minotaur archmages kicked off an Industrial Revolution by combining their patrons' superior technological knowledge with their own superior industrial philosophy, and the rest of the world's empires found themselves scrambling to catch up from the opposite direction (combining their own superior technology with the minotaurs' superior industrial philosophy)
The humans and the orcs have settled their differences and formed a multi-ethnic superpower together, and the Great War itself revolved around the humans and the orcs on one side versus the goblins (small and yellow-green), the hobgoblins (human-sized and orange-red), and the bugbears (tall, brown-black, extremely furry) on the other
The war eventually got so bad that both armies mutinied against their commanders together and refused to fight anymore.
I was originally throwing the D&D Kitchen Sink together (humans, orcs, elves, dwarves, goblins, hobgoblins, bugbears, lizardfolk, kobolds, dragonborn, tabaxi (catfolk)), but I decided to cut the dwarves, the elves, the kobolds and the dragonborn, and I brought the lizardfolk and the catfolk together into a single faction.
My new backstory is that there's some other continent off-screen that plays by more traditional dynamics (humans, elves, and dwarves being united against orcs), but that the first explorers from The Old Country to land on the main continent (populated by goblins and minotaurs in the north and lizardfolk and catfolk in the south) were humans and orcs.
These settlers originally brought their ancestral wars with them, but after a couple of generations, they decided they liked each other better than their overlords in The Old Country, so they joined forces and formed their own new nations together (forming alliances with the lizardfolk/catfolk against the goblins).
(In my original version, the minotaurs learned their new technology from the elves, but in my new version, they learned it from the goblins).
Worgs have also become more important :) In typical D&D settings, worgs are gigantic, demonic wolves that range from "domesticated beasts owned by goblins" to "sapient people who are technically enslaved by goblins and used as beasts, but are too bloodthirsty to care as long as their masters let them kill people."
In my Industrial setting, worgs more closely resemble gigantic hyenas (shorter tails and snouts), and their relationship with goblins is overwhelmingly that of an equal partnership — worgs are bigger, stronger, and faster, but goblins have opposable thumbs for making and using tools, and a worg mount and a goblin rider tend to be more personally close with each other than they are with their mates of their own species.
The cultural founding myth even says that it was two worgs who first proposed partnerships with goblins.