I've written a bit about this elsewhere but I can't find it at the moment, it's been on my mind recently, so I'm going to write it up again...
A long time ago I started to create a campaign world for Dungeons & Dragons. I never got very far, none of the places even have names, but I like the world enough that it has stayed alive in my mind ever since.
The core idea was an excuse to have a massive magical battle...
The main portion of the world is the SW, uh, portion of a continent. Bounded on the West and South by seas, to the North by mountains, and to the East by deserts and badlands.
The center of this area is a vast grassy plains with low rolling terrain and tall grass. This is cut by a great river and a old and well-traveled road. The road starts in the NW coastal kingdoms, tracks ESE into the grasslands before turning almost due East, and then continues across the prairie into the Eastern badlands. The river comes down from the Northern mountain far inland and wanders South before turning West and eventually meeting the sea on the West coast at a vast harbor lined with cliffs where it forms an immense waterfall.
A huge ocean of grass and low rolling hills. There are vast herds of aurochs and tribes of quicklings, bandits and nomads, strange beasts and monsters, etc. To the South it's always warm, to the North in the foothills of the mountains there is snow in the winter. To the West the ground rises in limestone karst and hosts forests, to the East the grass gradually gives way to badlands and desert.
This river drains much of the Northern mountains and the central prairie. It's huge and slow, and it serves as a major economic conduit bringing meats and skins from the grasslands and precious metals and gemstones from the mines in the mountains, and various luxuries and necessities from the SW to the North.
This ancient road connects the NW coastal kingdoms to the (unspecified) lands beyond the Eastern badlands. (I never filled out the far Eastern part of the continent. You can put whatever you want there.) It crosses the Great River not too far from the coast and then leads due East across the prairie. It's maintained for most of the way and there are way stations a day's ride apart for the first five days from the City at the bridge.
The further North you go the bigger the people and animals tend to get. The Mountain near the coast are home to giants, and between there and the northern fringes of the Western Kingdoms the people steadily increase in size due to intermarriage between humans and giants. There are rocs and dire wolves and huge deer and such. Dragons dwell up there. There are settlements, typically around specific mines, or in places where certain otherwise-rare creatures can reliably be found by dedicated hunters.
There are dwarves, elves, gnomes, living there each in their custom. The usual suspects. At some places the "Underdark" is close to the surface and Drow and other dwellers therein are known to have truck with the surface peoples.
The NW coast is a place of myriad tiny natural harbors and islands, there are lots of fish which support communities of humans as well as mer-folk, sea elves, and others including lots of nifty sea-monsters. Underwater or partially submerged caves are common.
Off the NW coast is a large island.
Below the Great Harbor the coast is much less interesting than in the North. It's mostly low cliffs and small beaches. The land isn't as fertile as in the North so communities are smaller and more sparse. It's pretty much a boring area where 1st-level characters can run around and get their bearings before going out into the other places.
A tiny mountain range marks the edge of the SW coast. It runs ENE to WSW and juts out into the sea in a rocky peninsula. This effectively isolates the Southern coast from the West coast. Just beyond the ridge the coast begins to bend around to the East. It's pretty much sand for miles with little creeks running down from the ridge, then the prairie and the southern coast run together after the ridge ends and there are some larger rivers leading South to the sea. The whole area is very warm, with mild winters. A few humans live here but the main population is lizardmen who dwell in the swampy Eastern parts of the coast.
Further South from the main continent is an archipelago of very nice tropical islands. My original idea was to set the classic "The Isle of Dread" module there but it never happened:
→ https://en.wikipedia.org/wiki/Isle_of_DreadThe main powers and groups of the land.
The primary economic engine of the whole region is the traffic on the road and river.
The other major factor is a ancient periodic war between the wizards on the island West of the Western Kingdoms and the City on the bridge. Every thirty years or so the wizards get together a huge army and schlep it up the river to lay siege to the city.
It's a kind of old traditional thing, and although people do get injured and even die, it's generally looked on as more of a festival or fair of sorts rather than an out-and-out battle.
There's an element of pageantry involved. Like a fireworks festival.
The point isn't to "win" (no one remembers what the original cause of the war was!) it's to show off the prowess and glory of the wizards and the lords of the city. They do things like launch trolls from catapults, or have specialist wizards who just do fireball or lightening. There's a special day of the battle where only undead fight, etc.
My original idea for the whole world is actually just this: it's a narrative setup for a massive magical battle! You've got this scenario where a massive magical army commanded by wizards gets to face off against a wealthy city that has had plenty of time to prepare, with an economy and ecology that can conceivably support things like trollapults and dragon riders, battle wizards and monster-troops! A sapping party that includes charmed umber hulks!
Grown up around the point where the Road crosses the River this is a large, rich, powerful, old city. There is no single king, instead each of the groups that feel they have a part in the rule of the land come together here to set policy and practice diplomacy. Each of the Western Kingdoms' various noble families keep houses here as part of their claim to nobility. The merchants who ply the river and the road have their main residences and warehouses here. The various folks that live around the land send their representatives, ambassadors, and warlords here to bargain and treat.
For example, the Drow Queendoms of the Northern mountains have treaties with the humans to prevent adventurers raiding their caverns and in return they refrain from raiding mines and such.
This is a large island West of the Western kingdoms that is populated entirely by magic-users and their support staff. There are a few large citadels that are basically magic schools where most of the people live and a handful of the most powerful and cranky mages have their own towers and castles about the place. They keep to themselves and mess around with magic and creating magical creatures and other magic-user stuff. Every thirty years or so they pack up all their best spells and monsters and sail up the river to attack the City. As I said, this is all in good fun, and more to show off than to actually win.
There's not enough land to grow all the food they need on the island, so while the island has a reputation of isolation and danger there is actually a pretty brisk trade between the mainland and the island. They import food and export potions, scrolls, wands, etc.
A lot of the wizards come from noble families of the Western kingdoms, so while there is again a traditional aloofness maintained it's mostly just a surface thing.
Lots of small kingdoms with tiny but rich towns based on fishing and trade with merefolk for pearls and other marine riches. Most of the families here have small but very fine and sturdy ships, and charming oceanic battles are the order of the day. The noblemen here are constantly attacking each other in romantic swashbuckling ways, revenging themselves, then reconciling and attacking the other guy together, etc.
It's considered *extremely bad form* to actually kill each other.
Being so close (physically and familially) with the Wizards of the Island *healing potions* are very common and no captain would sail without a full stock. In addition, these sea battles are typically concluded by grappling and boarding, rather than ramming and sinking, so gallant swordplay is the order of the day. This leaves plenty of time to let your vanquished foe quaff a potion to prevent death, so *not* letting them do that is almost unheard of. Also, merefolk will usually be on hand (if only to watch) and will save human sailors from drowning.
In fact, it's a rite of passage for a sailor to 'attend the Sea-King's Ball' as it's called. The sea-folk enchant them with the ability to breath underwater and put an on a feast while they wait to be ransomed. In the rare cases where the traditional ransom can't be paid (if a sailor has no family and his lord can't pay it for whatever strange reason) the sailor will usually be quietly returned in the night to some seaside village after a week or so, but some people stay voluntarily and join the merefolk society (or others...)
Anyhow these little kingdoms are jolly and even a little silly, and staunchly Lawful-Good.
The river reaches the sea at a vast waterfall. A nearly-circular cliff-walled canyon filled with water forms a natural harbor. It's roughly Ↄ-shaped (reversed C-shaped) with the river/waterfall approximately bisecting it. The Northern tip is a residence and workshop for wizards that specialize in light magic (they make lights of all kinds, etc.) The Southern tip is a fort and lighthouse. There is a connecting road that runs around the perimeter of the canyon/harbor (not too close to the edge) and a small city flanks the river on either side. Near the river there are lots of warehouses, but right along the banks there are nice houses with large docks that belong to wealthy merchants. There are more residences along the main road but most people live underground. The cliffs around the waterfall on both sides (and even under the waterfall and river somewhat) have been carved into galleries and corridors to the extent that it forms a kind of underground city below the surface city.
The chief business of this city is raising and lowering cargo between the sea and the river. There are large winches built and maintained by gnomes and powered by waterwheels from the river, and there are porters who earn their keep by hauling cargo up large interior ramps.
The city is run by the merchant's guild. It's very business-like and there's not that much to do or see here. There's a large population of people who live in and around the harbor with a great deal of interbreeding between various humanoid races to the point where they consider themselves to be their own culture. The lower and closer to the harbor someone lives, the more likely they are to have webbed feet or gills. In the depths of the city, especially in the old flooded parts, strange creatures dwell... (like a wayward aboleth or something, eh?)
In the Mountains near the West coast many giants dwell. They have a few towns but typically a family or two will have a hut made of piled stones or live a cave. Giants mostly keep to themselves. Some few put on airs and build castles and dare the Western Kingdoms to come fight them, but it's rare.
Young giants who want to fight usually enlist in the great war, for either side, so that keeps the giants' lands pretty mellow.
It's considered extremely bad form to harass or raid giants.
As I mentioned above, there is no clear division between humans lands and giant lands. The people and their livestock just get bigger and bigger as one travels North from the Western Kingdoms.
I don't know if these folk are copyrighted or something, so maybe I shouldn't call them "Quicklings"?
Quicklings were 2‑foot-tall (0.61‑meter) humanoid fey of slender build, similar in appearance to an elf, but with sharper, more feral features.→ https://forgottenrealms.fandom.com/wiki/Quickling
Anyhow, the main humanoid species that lives in the Great Prairie is a race of very small elfin-oid beings that are pretty nasty. They raid merchant caravans, harass nomads, and generally make the plains a pain in the ass place to live. They are the main reason why there are no farms or towns in the grass. On the road, where you can see them coming and they attack in small bands, they are not very dangerous. Legend has it that the few settlements that have been attempted over the years were all destroyed by hoards of quicklings who gathered together in the grass and overran them all at once.
Certain breeds of large hawks and owls from the mountains are specially reared and trained to hunt quicklings by the nomads who also live in the plains. Caravans typically hire at least a few of them for every trip.
As I mentioned before, when the plains start to give way to the sandy beaches to the South there are a lot of warm, wet, marshy areas that are ideal for Lizardmen (they are called "Lizardfolk" now, eh?)
→ https://forgottenrealms.fandom.com/wiki/LizardfolkThey are seldom seen outside the lands they prefer. The plains to the North are too cold and dry and the badlands to the NE are even worse. They mostly hang about doing lizardfolk things.
There are also some groups of humans living here but they are the Northern extent of people living in the Southern Archipelago, and culturally they are distinct from the humans living to the North.
(As I mentioned above, I originally intended to place "The Isle of Dread" module to the South of this area. I had a large human town on the coast North of the Isle, and there was some trade by ship around the little peninsula with the towns of the west coast. But you can do whatever you like with it, of course.)
As I said this campaign never really took off, so there aren't a lot of details, but here are a few odds and bods:
I envisioned this as a pretty "Rated PG" world (I was in high school) so there isn't a lot of evil in the world, and what there is is kind of like the villains on a kid's cartoon.
We played a Spelljammer campaign for a while and thought that was pretty great, so I always imagined this world as a part of "interstellar" society. That's optional, of course.
The "light wizards" aren't especially good, they're just into manipulating light as a magical art form. Magical light sources are common in the harbor city, and most of the wealthier folks have magical lamps and photon-artworks in their homes.
There is a coast road that runs from the Western Kingdoms to the Harbor that is not too well maintained, as most traffic goes in ships up and down the coast.
The area South of the Harbor is a basic 1st level setting.
Before you get too far North of the Harbor city the land starts to become a creepy moor, complete with mists and fogs, and a blighted feeling (although the area is *not* blighted, quite the opposite, it's actually a rich source of otherwise-rare simples.)
There are some small human communities scattered around, with sullen farms and shy, suspicious people. Lycanthropy is not uncommon, with whole villages going over to were-animal state. In this world it's a magical disease rather than (a set of) separate species, and typically people who have it often don't know it, at least until a significant proportion of the village is dead or infected.
Undead are very rare in this world. The dominant monotheistic religion is pretty diligent at clearing and sanctifying graveyards and whatnot, and because it's a pretty happy, well-adjusted world the conditions for undead to arise are almost unheard of. There are no liches or vampires or other physical undead of great power and sentience, but ethereal and astral or otherwise incorporeal undead are known: ghosts, etc.
In this world elves are relatively rare compared to dwarves, gnomes, humans, etc. However, elvenoid races are pretty common (like the quicklings of the Great Prairie) and often are of a partially trans-planar nature. (The preternatural speed of the quicklings is a symptom of their quasi-ethereal nature.)
This world is populated by all kinds of nature spirits, (dryads, etc.) which are the manifestation of the inner life or soul of the various outer "bodies" (trees, lakes, etc.)
In this context, then, the elves of D&D are not so much a race as a kind of higher manifestation of humanity, our better natures made incarnate.
So where does this leave the Drow? They represent the corruption of the higher nature, and as such they're pretty much as bad as it gets in this world.
I imagined this world as being kind of close to the other major planes of existence (in addition to being one of the rare worlds that had truck with "interstellar" space) and so weird creatures and effects are relatively more common here than in most worlds.
One way this shows up is that elementals are kind of common here. They tend to get used by mages to power various magic items (like the Flintstones' tech but with elementals rather than little dinosaurs.) Although they are common, they are typically not visible to people in everyday life (not *invisible* just "out of phase") but there are common spells (and certain places and conditions) that make it possible for people to see (and sometimes interact with) them without special magical preparation.
E.g. one not uncommon magical item that the Light Mages make and trade is a kind of lantern that has a small fire elemental inside, bound to service for a time (typically a year-and-a-day). These lanterns are very expensive and are most often used to illuminate the quarters of powerful mages and wealthy scholars and merchants. They are intelligent enough to recognize the lanterns' owners, obey simple commands, and even warn of intruders or other dangers. The trade-off is that they must be treated with respect at all times, and have meaningful work to do, otherwise they can become resentful or bored and cause problems.
There was a famous case many many years ago where a foolish mage had several of these lanterns installed in the hallways of his tower. With nothing better to do they quickly got bored and then went on a rampage and burned the whole place down.
It's not known what the Light Mages promise to the elementals in return for their service.
As a side-effect of the commonness of trans-planar creatures and magic there is a pretty brisk trade in counter-magic, and there is a whole sub-industry of forestry that prepares special panels of wood treated with strange potions and inscribed with potent sigils and runes *just* to guard against such intrusions. No wealthy persons bedroom or treasure room is complete without *layers* of extra-dimensional wards and guard spells.
There are no banks nor bankers in this world, instead their function is served (poorly) by an industry of dungeon builders. These guilds and specialists construct the traditional treasure chambers of the wealthy and powerful. These are built with traps, false paths and chambers, magic spells, and, for the really wealthy, living creatures up to and including dragons. (Young dragons will sometimes agree to guard the treasure of others in return for a yearly tithe in order to get their own hoard started.
While there are treasure halls in many places the biggest and most elaborate are in the Northern Mountains. Some of them are practically small underground towns with colonies of goblins tending various oozes and defenses.
Others are dusty forgotten relics, either looted already or holding ancient hoards.
The main problem here is keeping the locations a secret. (The traditional technique in our world, killing the builders, is out.) Two major techniques are used: a type of charm spell that leaves the person without memory of their actions for a day or two, or a kind of portal that allows people to move directly from place to place.
Both methods have their pluses and minuses. The charm spell only works for a few hours, so you have to get the workers close to the site, ensorcel them, and then get them the rest of the way before it wears off. This is relatively cheap but then the general location of your treasure hall is not a secret. The portal is very posh, but it's a huge PITA to set up and it only lasts a few hours. On the other hand, it keeps the location a secret, the destination of the portal can be placed by someone other than the casters of the spell that establishes it. You find a site, like a cave, go deep enough that people can't see the outside, and then chip off a chunk of rock to bring to the mages for the establishment of the far end of the portal. That way the construction teams can go in and set up shop without knowing where they are.