D&D makes a lot of tacit assumptions about how the game world works, and most campaigns naturally follow along. If you'd like a very different flavor, it might require only some tiny changes. Give a few of these a try.
Your fantasy world doesn't have to resemble England in the late Middle Ages. It can resemble any number of historical settings:
Or you can modify your setting any number of ways:
The Party:
Monsters:
Treasure and Magic Items:
Misc. Tips:
Alignment:
Religion:
I'm not terribly familiar with all the alternate game worlds from D&D's past (and present), but most seemed to make "little changes with big flavor":
Dark Sun
Magic. There are so many ways to tweak magic:
Your fantasy world doesn't have to resemble England in the late Middle Ages. It can resemble any number of historical settings:
- Primitive -- Imagine combat with spears, bows, hides for armor, etc. Dire Animals make great monsters.
- Ancient Greece -- Bronze age. If everyone's using bronze, you might not need any special rules for it.
- Ancient Rome -- Iron age, few long swords, lots of spears and short swords, soldiers in chain mail or breast plate (actually lorica segmentata).
- Dark Ages -- For most of the middle ages, plate armor was not available, and neither were the various reinforced forms of mail (splint, banded). Bastard swords and great swords weren't around, and many polearms weren't common. A soldier in a full hauberk of mail was a serious threat
- Arabian Nights -- You don't need the official Al Qadim setting to use rich Caliphs, desert nomads, caravans under attack from brigands, and wizards on flying carpets
- Mythic India -- Even a quick peek at the Indian epics reveals a world ripe for D&D-style adventure.
- Mythic Africa -- The Nyambe setting should be coming out soon.
- Mythic Hawaii -- Or any group of islands.
- Renaissance Europe -- Gunpowder, pikemen, halberdiers, lots of breastplates, but few full suits of armor.
- Age of Conquest -- It's eerie just how similar the Conquistadors were to D&D adventurers, going from place to place, killing (with "magic" weapons and armor) and looting, making some allies, then leading a big attack on the supervillain's castle (Mexico city, a metropolis of stone pyramids built on a lake in an extinct volcano).
- Age of Sail -- Pirates! 'Nuff said
- Age of Steam -- Everyone loves intricate brass clockwork, ironclads, and balloons.
- Modern -- D&D doesn't seem to handle this too well, but you can try any of the more modern d20 games, and you can mix in as much fantasy as you'd like.
Or you can modify your setting any number of ways:
- Put the characters into an alien environment and center the campaign around trying to get back to the normal world: Stranded in an alien world, shrunk down to the size of ants with no idea how to get back to normal size, trapped via a cave-in in a giant subterranean world that the surface world never knew existed (ala Journey to the Center of the Earth), sent forward in time to an alien future (Time Machine) or back to a primitive past, stranded on a deserted island, etc.
- Use non-standard structures in non-standard evironments. For example, when most people think of pyramids, they right away think of the desert. How about placing them in the snowbound north?
- Place the campaign under water, using aquatic races.
- Have no safe haven, no Village of Hommlet, to return to. Keep the heroes on the run.
- Use evocative names -- for characters, places, and magic items. Rune's quasi-oriental setting uses Adjective-Noun-Verb names for men and Noun-Adverb-Verb names for women. Names like "Thorin" were evocative when they were new. Names like "Mad Stone Tumbles" still are.
- Don't be afraid to alter reality. This is a fantasy game. In Ravenloft, for instance, the Mist can alter time and space. If the seasons change daily, or the landscape moves when you're not looking, you're in a fantastic realm.
- No common tongue.
- A lot of fantasy fiction describes a world where humans are a young race, much younger than the elves and dwarves. Have primitive humans wielding clubs and wearing hides while already advanced elves and dwarves wield steel blades and wear steel mail. Further, have the illiterate humans casting only the simplest of spells, if any.
- Magic, monsters, and demihumans are all thought to be fairytales. It isn't until the PCs get out in the world and begin to explore that they find out these things are real.
- Magic exists but there is a secret society that suppresses knowledge of magic and it's use, by any means necessary.
The Party:
- Have the heroes be the only spellcasters in the world -- or the only good spellcasters in the world, hiding their powers from their evil enemies.
- Have all the players run characters of the same race and class: a troop of mercenaries, a band of outlaws, an order of knights, whatever. Not every party has to be the fellowship of the ring.
- Have the characters either be a family or have families (or start families).
- Invert which races are good and which are bad. Play the Orcs, Goblins, and Kobolds against ruthless Elves.
- Let the characters play the villains, plotting to take over the world and controlling their evil armies. Let them fight of bands of adventurers trying to stop their reign of terror. Afterwards, let them play adventurers taking on the villains they played earlier.
- Have the heroes all be animals, either in a campaign full of anthropomorphic animals (e.g. Redwall) or in a normal "human" world.
- Have the heroes be children.
- Have the heroes be retired has-beens, showin' the young bucks how they did in their day.
- Have heroes of vastly different power levels. Perhaps one character is the squire of the knight, or the familiar of the wizard.
- Have the heroes be normal people: farmers, merchants, scribes, not knights and wizards.
Monsters:
- Eliminate monsters. Or keep them in the background awhile. Fighting human enemies should be plenty exciting, and when the evil sorcerer finally summons his demonic allies, it means something.
- Stick to just a handful of monsters. Choose either goblins or kobolds or orcs as your cannon fodder, and rely on class levels or different equipment to differentiate them. (What's Your Monster Palette?)
- Base your goblins and elves on folklore, not modern fantasy. Have them rely on magical deception (not studded leather and a morningstar) to get the job done.
- Have the monsters be something that can be dealt with by wits, such as with riddles or tricks. In folklore, magic is often just knowing the strengths and weaknesses of various beasts, knowing what they like and dislike, knowing how to talk to them, etc. The key to killing the dragon isn't having a stronger sword arm; it's knowing that the dragon has a soft underbelly, and if you dig a ditch, he'll crawl over you and expose it.
- Give every monster a special weakness -- just like vampires who can't stand sunlight or cross running water and Middle Earth trolls that turn to stone in sunlight. The Raksasha can't take blessed crossbow bolts; maybe a Balor demon dies if it gets pure silver in it's eyes; a Beholder take great damage from salt in its central eye; Black Unicorns can't take the dust from the crushed horn of a White Unicorn; evil Fey can't stand the ring of pure silver bells.
- Don't forget animals. Talking animals are a staple of fairy tales and fantasy, and some animals are natural predators of monsters the heroes might face (e.g. mongoose or weasel vs. basilisk or poisonous snake, giant owl vs. dire rats or were-rats, tiny mouse vs. elephant, etc.)
- Have an enemy. Despite all the dark overlords in fantasy fiction, few of them last past an adventure or two in D&D.
- Night of the Living Dead. Don't disable zombies at 0 (or negative) hit points. Have them keep coming down to -10 hit points, but have each hit take off a limb. Graphically describe it, and give the zombie reduced abilities: leg, can't walk, can only crawl 5'; arm, grapple at -4; head, drops "dead" (a la Night of the Living Dead), or simply can't change what it's doing.
- Unique Monsters: one Pegasus, one Medusa (with two other gorgon sisters), one Minotaur, one Questing Beast, one Fenris Wolf, one Midgard Serpent, etc.
- Tie the origins of certain “classic” monsters to the world itself. For example: Medusa from Greek mythology dared to compare her beauty to that of Aphrodite and was punished. Where do Medusae come from in your world?
- Every monster has a purpose: No "natural" monsters. The Dark Lord created Orcs to fight his enemies; they're not just another race.
- Use unusual classes to create interesting monsters, e.g. Samurai Orcs.
- Give races a new theme, e.g. Frost Elves, or Bugbears as northern Ice Goblins.
- Switch around monster descriptions but keep the old stats.
- Have Orcs or Kobolds or some other "lowly" races rule over the other races.
- Maybe Necromancy isn't evil at all, and Zombies and Skeletons make good laborers.
- Add new flora; don't dwell so much on animals.
Treasure and Magic Items:
- Have magic items be gifts from powerful allies, not loot from enemies (who have an odd penchant for leaving magic cloaks in the closet).
- Have Knowledge (History) provide characters with the names of weapons, their powers, any magic words they need to activate them, etc. That way the wise wizard (who really should have plenty of knowledge skills) doesn't cast a spell to uncover an item's powers; he looks it over, mumbles to himself, then announces that this must be the long, lost whatever, used in the great wars against whomever's army, etc.
- Have magic items' powers reveal themselves to the characters gradually, based on their actions and what they learn about them. Rather than having a Fighter find a +2 sword and ditch his "worthless" +1 sword, he can discover new powers in his original sword with the help of the wizard (or ancient elf, or crotchety dwarf, or talking animal) he rescued.
- Provide treasure with a place in the world: armor once worn by the current king in his youth, works of art by a now-mad mage, historical documents, etc.
- Heroes will only have one or two magic items their whole careers. Hand them out early and at full power. That's all they will ever get, but it's their ticket to glory.
- Remove the limitation that all magic weapons and armor have at least a +1 bonus. Also remove the limitation that bonuses are always applied to both to-hit and damage.
- Give most magic items significant drawbacks and curses.
- Have items gain magical abilities through their usage and history rather than through enchantment.
- Don't use any magic items from the DMG. Instead create all original items. Alternatively, swap the item and the effect. For example, have a crown of invisibility and a cloak of intellect.
- Ignore D&D's definitions of admantine and mithril, and have all magic armor made from those materials. (That works quite seemlessly in a Middle Earth campaign, of course.)
- Disposable magic items. The token, whatever it may be (a favorite brooch, a lock of hair, a handkerchief) is imbued with power, unintentionally, because of the emotion put into it. Say your fighter saves the miller's daughter and she weaves a necklace of flowers for him as a thank you. Maybe it will negate the next critical hit that is made against him and then it crumbles to dust? Maybe it will give him +1 to his saves until the flowers wither.
- Replace scrolls with talismans (from Oriental Adventures).
- Remove one-shot scrolls. Scrolls are no different from pages out of a spellbook. You can learn a spell from them, but they don't store any magic energy allowing you to cast from them.
- Allow casters to cast directly out of a spellbook (or from a scroll) -- slowly, with a chance of error.
- Remove charge-em-up wands, rods, and staves.
Misc. Tips:
- Drop the "flavored" classes. Ranger, Paladins, Monks, Bards, Clerics, and Druids all bring a distinct "D&D" flavor to the game. Optionally, make their class abilities feats that other classes might take. Let Fighters take Rage and Favored Enemy as feats.
- Try a different set of combat rules, like Ken Hood's Grim-n-Gritty Hit Point and Combat Rules or any variant that doesn't keep giving extra hit dice ad infinitum. Instead of increasing hit points, you can increase armor class. This makes magical healing less necessary, even if you keep the heroes at roughly the same power level.
- Start off the Party at something than 1st level. Higher level characters need more obligations, worries and aspirations.
- Fixed levels. Just start everyone as heroes (e.g. 7th level) and keep them there.
- Base the game completely around non-combat advancement. E.g. XP for converting the "unsaved" to your religion, or for finding ancient tomes
- Don't assume N gold pieces will get you N gp worth of stuff. No one said you were in an efficient market economy.
- Use the barter system. Eliminate currency. This will allow for more role playing interaction and the use of CHA based skills more oftern.
- Have the enemy play rough and play smart. Have them use tactics and magic as PCs would.
- Don't match every encounter to the PCs' abilities. If the enemy's caught off guard, they should be vulnerable; if they know what to expect, they shouldn't be.
- Use fantastic elements to dramatic ends. A Black and White season has no in-game effect, but -- Wow! -- it packs a dramatic punch. What would your players do if it started raining blood? In a fantastic setting, you can go well beyond a mere dark and stormy night.
- Tie the players to the world. If family ties and honor matter, the players will start to behave with filial piety and honor, not as thugs looting from weaker thugs.
- Status. Introduce the Reputation statistic from Dragon Magazine. Rep=Lvl+Chr bonus+Bluff+Diplomacy+Intimidate.
- Honor. Use the Reputation statistic from above but substitute more "honorable" skills for Bluff, Diplomacy and Intimidate.
- Change the way things are named or viewed from region to region. In one country, the All-Father is Wotan; in another, he's Odin.
- Most of us realize you can use Oriental Adventures to give an exotic flavor to foreign cultures (human or monster) -- but you can also strip the oriental names off most of it for decidely occidental cultures too. Samurai as Knights, Shamans (replacing the martial-arts Feats) in place of Clerics or Druids, arcane Shugenja as elementalist Wizards, Wu Jen as Wizards, Bear Warriors for Tolkien-esque Beornings, elven Blade Dancers, Eunuch Warlock as a non-eunuch specialist Wizard, Kishi Charger as Cavalier, Ninja Spy as mystic assassin, etc.
- Have an explicit "Winter Phase" or "off season" between adventures, where the heroes handle crises at home, start romances, raise families, craft magic items, etc.
Alignment:
- Remove alignments.
- Use Good and Evil or Law and Chaos.
- Divvy up the world into two sides with each considering itself Good and the other Evil.
- Track alignment as carefully as hit points. Use Pendragon-style trait pairs, but just use two: Lawful/Chaotic and Good/Evil.
- Use all 13 Pendragon trait pairs (Chaste/Lustful through Valorous/Cowardly), and divvy them up between two mega-trait pairs: Lawful/Chaotic and Good/Evil.
- Use alignment only for Outsiders, Clerics, and Paladins.
- Don't tell the players that their characters' Detect Evil powers are purely delusional. Let them play religious fanatics who feel justified by their "divinely revealed" knowledge. Optionally, after enough wholesale slaughter, let them know the truth.
- Place the characters in situations that require them to make moral decisions. If you're tracking alignment, these moral decisions can have in-game effects.
Religion:
- The gods that people worship may not be gods, but just historical heroes long dead.
- As in real world polytheistic societies, have no rival churches or Clerics dedicated to a single god. Individuals pray to whichever god in the pantheon is appropriate for their situation at hand.
- Have religious differences be a matter of opinion rather than different gods. Make the 'evil cleric' a heretic who believes opposite of what the established church authority believes instead of a worshipper of an evil god.
- Use sects and orders to introduce diversity. That way the cleric of the god of magic becomes a member of the Order of Saint So-and-So, who's members are reknown for their knowledge and skill when dealing with magic.
- Instead of having the large, classic gods, use small gods that take the frm of huge beasts, terrain features, or monuments. Clerics can only cast spells (or "recharge") within range of the small god.
I'm not terribly familiar with all the alternate game worlds from D&D's past (and present), but most seemed to make "little changes with big flavor":
Dark Sun
- Magic destroyed the world and is now a capital crime.
- Psionics everywhere.
- Desolate desert terrain and climate.
- Variant races and classes.
- PCs are "blooded" scions.
- Low magic -- but the "blooded" can wield high (normal for D&D) magic.
- Heroes don't just adventure; they rule the land.
- Variant races, a bit more "classical" in feel (except for Halflings).
- Magic tied to the moons and alignment, one mages' guild.
- Return of gods (and clerical magic)
- Monster palette: draconians, chromatic vs. metallic dragons
- Race palette: kender, tinker gnomes, gully dwarves
- Monster palette: vampires, werewolves, ancient dead, goblyns.
- Evil is tangible, and evil acts transform the evildoer.
- Detection magic doesn't work flawlessly, so our heroes can be kept in the dark.
Magic. There are so many ways to tweak magic:
- Raise the magic level!
- Remove magic entirely. Perhaps the heroes rediscover it. Perhaps their arch-enemy does. Or maybe there just isn't any magic for once!
- Remove divine magic; the gods have fled, or they simply don't hand out magic powers.
- Remove arcane magic. Evil "sorcerers" are evil priests worshipping dark gods.
- Remove spellcasting entirely. Have all magic through magic items.
- Assume a more "primitive" (or secretive) level of magical knowledge. Have no known spells; all spells must be researched.
- Implement priests as Sorcerers or Wizards (with the Cleric spell list) so that they're wise men, not warriors. Same with Druids. Make Turn Undead a 1st-level Cleric spell, and have Druids cast Polymorph Self to shapeshift.
- Let Clerics turn any and all supernatural creatures not just the undead. In folklore, goblins and trolls can't stand the sound of church bells.
- Make the spellcasting classes prestige classes with prerequisites. After all, isn't it odd that a Bard with four skill ranks in Perform is good enough to enchant people with his music? And that a Druid who barely knows his way around the woods knows enough of Nature's secrets to command it? Should every religious figure wield powerful magic? On a daily basis?
- Don't give back spellcasters their full power after one night's rest and some study/prayer time. Make recharging require rare magical ingredients, or blood sacrifice, or a selfless act of piety. Or simply make it take longer. That way spellcasters won't toss spells left and right, but they'll have them for when they need them.
- Make spellcasting always take a full round or more. Suddenly spellcasters aren't video game characters.
- Have magic transform its user. Over time, necromancers grow pale and withered. Fire mages start giving off sparks when angry; eventually their hair turns to living fire. Shapeshifters take on the traits of the animals they become.
- Limit all sorcerers to a strongly themed spell list. For instance, a "fey" list of just: daze, dancing lights, ghost sound, prestidigitation, obscuring mist, charm person, hypnotism, sleep, change self, ..., polymorph. Or a summoner list of just the Summon Monster spells.
- Make an entire magic system out of summoning (e.g. Elric).
- Eliminate all directly-damaging spells. It's not like wizards can't do any harm without magic missile and fireball, and they're certainly more interesting that way. Or just make all those spells more difficult. Besides, isn't a wizard supposed to turn you into a frog?
- Make all magic easy to "track" with Detect Magic, so covert spellcasters won't want to cast indiscriminately. Make flashy evocations (e.g. Fireball) particularly easy to track.
- Remove the Arcane Spell Failure percentage for armor. In a campaign world like Elric's Melnibone, sorcerers freely cast in full armor.
- Remove the distinction between Arcane and Divine magic. Is there a difference between an evil sorcerer and an evil high priest?
- Increase the distinction between Arcane and Divine magic. Have quasi-Christian priests whose only real powers are dispelling fiends' enchantments, banishing demons back to hell, etc.
- Dark Side points for spellcasting. Have every spell force a Will save (DC 10 + 2 * spell level) or the caster gains a Dark Side point. Once the caster accumulates more Dark Side points than Wisdom, he goes mad with hunger for power. The Dark Side points can cause a cumulative penalty to later Will saves too -- wonderful for that downward spiral effect.
- Runequest Magic. Just about anyone can cast minor spells: no multiclass penalty for a level of Sorcerer.
- Different Magic for Different Races. Humans must learn magic as Wizards, Elves are naturally Sorcerers, etc.
- Require that all Wizards specialize in one school, and they can only cast spells from that school
- Tweak spells. Lightning Bolt can become "Fire Line" with no real game balance issues. Fire Ball can become Ice Ball and so on.
- Eliminate magical travel (teleport, whispering wind) so the easiest way to travel from one village to the next is still on horseback.
- Invisibility doesn't make you invisible; it merely makes you ethereal.
- Have Wizards learn their spells from their familiars -- who are the ones in charge. The familiars are training their wizards to fight their battles for them.
- Allow meta-magic (or some other mechanic) to vastly increase the size and duration of thematic spells so the Dark Lord can blanket his kingdom in perpetural darkness, and the White Witch can blanket her kingdom in perpetual snowy winter.
- Require rare material components, e.g. a chicken egg hatched by a toad at midnight of midsummer's day, a lock of a lover's hair, etc.
- Have "preparing" a spell mean storing it in a wand/rod/staff or talisman instead of "hanging" it in memory. Taking a Wizard's staff away or breaking it means disarming him of his prepared spells (or most of them).
- Use Call of Cthulhu magic.
- Use Star Wars Force rules for magic.
- Use Psionics for magic.
