What's needed for a Setting?

I've been playing in Nick of Paper & Pencil's "Warlock Moon" game lately and it's interesting to watch.  Nick's a meticulous GM when it comes to designing his levels - the paper shuffling in the background, quality and quantity of tricks/traps, and hint of a multi-level notation system confirm this.  Yet, Warlock Moon is still a setting in it's infancy, two session have been run, and the ideas and feel of the setting are still being hammered out. Watching this process, and doing setting work of my own on the Apollyon, I've been thinking about the question "What's the minimum of resources one needs to run a compelling and unique setting".  I mean most people who've played a game of D&D or even stumbled about Skyrim for a few hours could gin up an amusing enough vanilla game with a system book and a piece of graph paper.

You can get going with something along the lines of "goblins have been killing farmers, and you're the local tough guys".  Cave map, some goblin stats and instant cliched default game setting. This isn't what I'm talking about, though these sorts of games can be fun, and can grow interesting as the world expands organically.  What I want in a setting is something that has a distinct feel, different from what one can get in a million other places.  In order to do this certain considerations must be made.

1.  CORE IDEA: This seems obvious, your setting isn't going to be much if there isn't an idea behind it.  Anything will do, historical or fantastic. Warlock Moon's core idea seems to be "Logan's Run as Fantasy".  The HMS Apollyon's core idea is "Victorian/Edwardian Hell - On a Boat".  One has to check this idea on a few axis to see if it'll work.  1) Is it big enough for a setting? 2) Can it be played as the kind of game you want?

EXAMPLE: Eastern Europe post Mongol Invasion, except the Mongols are Fey necromancers.
Answer to Question 1:  Yeah, cultural collision with dung ages humanity meeting an alien culture both barbarous seeming and highly advanced has a lot of room for setting. We've got elven horse archers (the most important of them on undead steeds) moving over the shattered lands of a traditional medieval style fantasy world.  The locals of course are baffled and horrified as they return to their burnt villages and find the dead enslaved and working the land.  Maybe the nomad yoke is light enough, but the whole idea of giving up 1/2 of one's acreage and turning over one's dead to work it galls.  We've got the jeweled capitals to the far East (or West if one wishes to reverse the directions for kicks), themselves assimilated into this nomadic elven empire with sorcerously and technologically advanced subject peoples.  Yeah there's a lot in the history to steal from and the fundamental conflict here is sound (though I wouldn't make the elf nomads the enemy exactly).
Answer to Question 2:  Well I like OD&D so would the Empire of the Elven Khans make for a good OD&D game? Yeah I think so.  The endless ruined lands of pseudo Kievian Rus are filled with wilderness travel and sites for adventure.  The ruins of sacked cities, the barrows of dead kings, even ancient pseudo-Roman or pseudo-Song sites filled with forgotten treasures of long fallen empires.  The whole idea of a Dark Ages/Early Medieval style post nomadic invasions campaign seems to work with OD&D's life is cheap philosophy and larger party sizes.  Players can be a band of refugees, monks, a displaced noble, or even an Arban of elven Keshiks and local auxiliaries.  Thus this could work as a setting.

2. AN EVOCATIVE INTRODUCTION:  Now when telling players about a setting, there's the old standby of writing up a big document of history, peoples, customs and all that.  You can give this to people (who won't read it) or lecture your players about it and watch them drink beer and doze off. Obviously I am not pro-massive information dumps of setting material.  Of course before playing a new game, the players will do some stuff - roll up some characters.  They will even be willing to listen to a paragraph or two of setting fluff to give them the idea of what kind of characters they might play.  Best way to do this seems to me to be equipment lists, as these give one a sense of what's valuable and what's different. More important they provide an idea of the scarcity or availability of things in the environment. One can use the standard lists from a game, but it feels better to augment these with unique items.  Obviously unique classes and races serve the same purpose, but they aren't necessary.  In a mechanically simple game like OD&D new classes aren't usually necessary as the traditional ones pretty much cover all the archetypical bases.  Spell list changes would be good as well, but I don't think they are necessary for rolling up the characters and getting into the game. The only other thing I'd do would be include some art resources (plundered from online of course) to get the players thinking about what their PCs look like.  In this case the Ivan Bilban below pretty much makes the setting.  The art is useful for the GM to, as it can help get the idea of what needs to be described to get the feeling that the setting deserves.  Here for example, the bright colors of the gear and the oddly skeletal trees in the background are both good descriptors to take away.

Can't beat Ivan Bilban for evocative.

EXAMPLE:  Equipment in the lands destroyed by the Necro-Fey Nomadic Empire (that needs a new name) is hard to replace, but characters will have a standard selection of starting equipment.  Even plate mail, in the form of Cahparact style scale armor or "mirror armor" is available, but it is uncommon and very dear.  Other wise what is important to consider is what's valuable and special.  Among people living on the steppes horses seem very important, both as a means of transport and as wealth.  Thus we will need a list that has a few types of horses on it.  Likewise, the distinctive weapon of central Asian horse nomads was the compound bow.  These bows are desirable, both because they can be used from the saddle, are more powerful than hunting bows and can be fired very rapidly by a trained user. Both of these need to be on the equipment list.  Now since the Nerco-Fey are both barbarians and necromancers I suspect that they should have a small necromancy based spell list, and access to special shamanistic sorts of limited magical items relating to the dead.  Nothing too flashy I think.

Horses:

1. nag or workhorse - 10 GP
2. steppe pony - 50 GP
3. courser - 80 GP
4. drestrier - 200 GP

Now all PCs should start with at least one horse - say a steppe pony or courser.  Additional horses are needed for longer rides, and no one except the destitute travels by foot.  Horses are also the most common form of currency, and a rich man is more likely to have a string of horses than a purse of gold.  Mechanically I think the difference would be a bonus or penalty to Dex checks to do horse tricks, additional movement overland and maybe an extra die on chase roll.  Also combat bonuses for drestriers and coursers against enemies on foot.

The Necro-Fey undoubtedly have tireless skeletal horses, flying ghostly horses and horrible Frankenstein style monster horses of enormous size and strength.

Special Equipment:

1.  Compound Horsebow - range as longbow, may be fired from horseback or indoors.  DAM 1D6+1 or two shots per round with hits doing 2x1D6 take the lowest. 50 GP.
2. Mind Salt - Refined from the powdered undead brains of shaman and magic workers, swallowing or insulfating a dose of this gray crystalline dust will allow one to speak with the dead. The dead need not speak back, and cannot be compelled to answer.  Most of the dead are confused, angry and will want things in exchange for information.  Excessive mind salt use rots the sinuses, tongue and teeth. 80 GP.
3. Bone Gris Gris - tied together with steppe grasses and sinew these conglomerations of bones are nauseating and upsetting to undead and will drive them away when burnt.  A bone gris gris will turn undead as a level 1-4 cleric while burning (for two turns).  Unfortunately bone gris gris are also off-putting and nauseating to the living and only one can be carried by an individual per level - 120 GP 
4.  Lamellar Armor - A light strong form of armor favored by the lancers of the Necro-Fey, while not as strong as the plate armor used by human knights or the mirror armor worn by the Necro-Fey's client states, it's weight, ease of repair, ability to be crafted from non ferrous materials and relatively simple construction make it the armor of choice for non-human warriors.  AC 4, non ferrous armor that is as encumbering as studded leather - 200 GP

Another amazing Keith Thompson work.

3. EVOCATIVE ENVIRONMENT:
Even if one plans to run a particular locale for the first adventure, rumors that discuss other possible sites are a good to give the players more knowledge about the game world and remind them that they aren't stuck doing what the GM says.  Rumors and hooks are good because by letting the GM know which rumors interest them, the players can inform the Gm what sort of content needs to be created for the next session. Updating rumors and distant events is helpful to create ongoing tension and grant player's agency, but it's most important about letting the player's know what is important in the environment. Equally useful is an starting town.  A starting town that has some feeling of place. Nothing too complex, just a few descriptors and an idea of how the town is run, with some attention paid to it being a lawless place where a band of tomb robbing drifters won't be too stymied by the authorities.
 
EXAMPLES: Note that these ideas for setting hooks and such flowed pretty easily once one gets a solid main idea, and aren't just informed by the fiction I've created/bricolaged together, but by the needs for a sandbox style OD&D game.  I'm also not trying to sketch out the whole setting, just enough to give it a feel that the players can latch onto and hopefully build much of the world for me with.

Example Part I: Rumor Table and Adventure Hooks. As mentioned above rumors and hooks create setting and hence form a basis of setting.

1. Worms - The steppes are haunted by red death worms, some as big as old tree trunks. The worms are more common now after the invasion, maybe the Fey brought them.  Wherever they came from they are dangerous and will burst from the earth to tear out a horse's belly.
2. Burnt Monestary - To the North a ways are the still smouldering ruin of the Monestary of St. Bazil.  The monks managed to annoy the Fey by concealing some treasures.  It went badly for the monks, but a day into the massacre the Fey detachment rode off quickly, having not sacked the place with the thoroughness they are known for.  Treasures might remain, even relics, and there might be a monk or two hiding out in the ruins.
3. Nearby Town - More distant than St. Bazil's Monsetary, the shattered capital of the duchy sits a barren waste of bones, some animate.  While the town was undoubtedly looted clean by the Fey, as everyone knows the nomads a loathe to dismount from their horses and fear going underground.  It's likely the catacombs, cellars and dungeons of the city are still intact.  Additionally their must be some survivors and they would undoubtedly give up the wealth they've saved for supplies of food, seed and tools.
4. Undead Hordes - The Necro Fey shaman aren't always the most restrained in their reanimation and many of the battle sites and sacked villages contain milling or wandering hordes of animated dead men.  Used briefly to aid the Fey in a sack or battle, these sould call to be returned to the peace of death.  Also a lot of the time the bodies (especially those of soldiers) have valuables that can be looted.
5. Suebi the Unforgiving - Not all the Necro-Fey ravagers have continued East to new conquests, most of the nomads remaining are content to boss the locals around, demand tribute and keep the peace but a few are real demons.  The golden eyed Suebi the Unforgiving is one of the later, an outcast among his own people, he rides with an arban of reanimated horsemen and a few dedicated living followers and leaves death and evil in his wake.
6. The Order of the Blue Flame - The Blue Flame are an eastern religious order of warrior monks.  They were mostly all slaughtered in a battle to the East, but some small bands supposedly escaped.  Most are like other groups of wandering, lost fighting men only perhaps less destructive, but some of the orders fanatics believe that the gods demand the complete annihilation of the Fey and any who accept the Fey dominion.  The knights been using this belief as justification for atrocities on travelers and small settlements.
7. Ruins - The old empire had an outpost to the West a ways, it's mostly just a mound of grass, and everyone says it's haunted, but you can see strange stones worked into the villages around there.  The ruins might have been a temple once, likely to the bull slayer, their warrior's god. Those ancients always kept strange grave goods under their temples and were fond of gold artifacts.
8. Tears of Heaven - Travelers from the West and even the Fey talk of gems that rain from the sky in times of trouble.  These magical "tears of heaven" are sometimes found in great drifts to the West, most often in the deserts and with all the trouble in the world, now has to be a good time to go prospecting for them.

Example Part II: New Monsters.  Sure one should have more than one new Mosnter, one should have at least five to start with because five monsters can pretty much fill the rumor table and include all the basics 1. Horrible Beast (Owlbear replacement) 2. Organized Opposition (Goblinoid Replacement)  3. Otherworldly Nightmare (Wraith/wnShadow/wight replacement) 4. Horrible Vermin (Slime/Giant rat replacement) 5. Horrible Brute (Ogre replacement).  Encounters can be filled out with animals, boring undead and such at first.  Now for a pseudo-Mongol invasion game going directly to the mythology and folklore seems good.  There's a cryptid called a "Mongolian Death Worm" or "Intestine Worm" that is supposedly a large bright red worm that lives in the sand of the Western wastes and spits acid.  Sounds pretty good for either a Horrible Beast or Horrible Vermin depending on size.

Red Death Worm: HD: 4 AC: 5 ATK: 1 DAM: bite 2D6/spit 1D8* MV: 30'/Tunnel 10' SV: F3 ML: 12

The death worm is an ambush predator that burrows beneath the steppe and desert, bursting forth to prey on heard animals.  The worms represent a danger to humans, as they cannot determine or do not care about the difference between a party of horsemen and a herd of wild horses.  Worms may also be encountered by fools who choose to delve into the subterranean ruins of the ancients, as the beasts prefer to lair in such places, safely out of the sun.  Worms range in size from 2' to 12' long and their long glistening, intestine like bodies can be as thin as a human forearm or too large to wrap both arms around.  Death worms attack with a tooth ringed maw, or by spitting digestive acids at creatures at a range of 40'.  The acid of the Death worm is powerful and in addition to melting flesh and sinew, will damage armor and weapons (either organic or metallic) on a failed save vs. poison.  Armaments corroded by the worm's spit will suffer a 1 point penalty to Armor Class or Damage and to hit, while equipment such as ropes will be destroyed.

Knowledgeable travelers claim that the Death Worm much prefers the flesh of horses to that of men, and that the creatures will rarely pursue riders who attempt to escape while the worm or worms devour their animals.

Example Part III: Starting Town.   let's call it Moriya - which is almost a real place (Merya or Galich) that was really sacked/conquered by the Mongol invasion of Europe.  The real town was a salt mining center, and that works here as well.

Moriya is still a town, or at least the remnants of one, having been sacked by Necro-Fey nomads a year before.  It wasn't an especially brutal sack, and many of the local population managed to hide in the thick forests near the river (a tributary of the the Great Mother River known as the "Green Mother") or cowered in the salt mines.  The local nobility and soldiers were largely killed, enslaved or exiled, and Fey ger now dot sit in the town's fields, but Moryia avoided being turned into a desolate waste of dust scoured bone.  While the town was of moderate size before the sack, and growing in wealth due to the salt trade, much of it was burnt, and a newer town, rough and a bit unmanageable has been built closer to the salt mines.  The Fey, now content to act as overlords, not plunderers, are protective of Moryia to a degree, as it provides a tribute in valuable salt, but the day to day powers in the town are a council of three or four merchants, some from the distant lands ruled by the Necro-Fey.  These merchants are both the cause of Moryia's rebirth and the source of its troubles, hiring bands of armed men and seeking to seize salt deposits from each other.  The merchants are happy despite their squabbles, and trade is growing as new partners are found (the old trading partners having largely been destroyed by the Necro-Fey), but they will violently resist any effort by either Necro-Fey or exiled local nobles to claim the town if they have any chance of success.

3. AN ADVENTURE - Now I've got what I need to organize my own thoughts about the setting, so how about a putting together an introductory adventure.  Personally I like to make one that covers a lot of ground to start with, and so I want to include several of the hooks above in a single adventure.  Mostly as a way to avoid extra work, but also so the players can immediately follow the thing that gets them excited from the hooks.  Only the monastery seems close enough, and I can see making it a small map.  Once the party gets there we'll have Suebi holed up inside with a band of Blue Flame outside trying to kill him.  Crazy monk survivors and some restless dead.  The Monks want to be left in peace, but Subei and the Blue Flame are trying to murder them, and each other. Undead running about, clerical spells flying here and there and some trapped catacombs that saved monks might help the party into.  At the end of the adventure we've most likely gotten a band of fanatical crusader types and a evil cult of Necro-Fey mad at the PCs.  if they're lucky they have a saint's finger bone and some friendly monks.  Now the other options (temple, capital, prospecting) are all some distance away, and an introductory hex crawl might be in order.  Easy enough - I need a few random encounter tables that evoke the majesty and vastness of the steppes while amping up the creepy of the post apocalypse aspect of the invasion.  The actual location can be explored in session two, once I know where the players are headed, and that gives me time to map and key that locale.

So ultimately what I've got to have a setting ready to run is (in order of preparation) 1. An idea about the game world as a whole 2. A novel addition or two to the equipment list (creating the ideas of necromantic magic as central, non-humans limited to non ferrous armor and weapons, horses as currency/wealth, and archery as preferred combat art.  2. A rumor list with hooks 3. A few unique monsters 4. A starting town 5. A starting adventure that introduces some factions in the world.  I should also note that this setting is pretty close to the rule book defaults - a medieval fantasy.  By basing it on Eastern Europe I may perhaps be accused of exotification or orientalism, but I think the ability to pull cliches and real history in makes for easy content generation and a low player buy in (they don't need to learn game world fluff so much).  Not sure if I'd actually play this setting - but it feels pretty cool.  I like the idea of shamanistic elven necromancers with compound bows and a taste for conquest.