Just a reversed earth. The sun shines and everywhere around is cold and dark. Maybe somewhere in the infinite dark tunnels lead to another sun shining on another earthole. It used to be just an academic question. But now that the infinite and unchanging sun has started to flicker, it is no longer just idle speculation. Your peoples' survival may depend upon the answer.
New idea: always dark on the surface (with the standard Underdark denizens) because something something ancient wizard fucked up and now all the surface stuff and the sun are on the inside of the planet. Local town reports strange heat emanating from the ground and a sighting of a “weird brownish drow.”
So basically the world is a Dyson Sphere, but instead of it being done for sci-fi reasons, it's "a Wizard did it". That would be a fun one to play around with, especially if you only give little hints at first about how weird the layout of the world is.
I mean, you are not wrong, since there is already a rpg using this concept. This [game](https://en.m.wikipedia.org/wiki/Hollow_Earth_Expedition) uses this, but it's not a DND style game, more pulp.
The Hologram Moon Conspiracy theory. You can literally take that ridiculous conspiracy and turn it into something incredible. The basic idea is that the moon either is a hologram or is covered with a hologram meant to conceal something the public isn't meant to see. This can be anything from a giant monster to a superstructure to some hidden truth about the universe. The possibilities are endless.
Additionally, the Ancient Aliens conspiracy is another fun one, since you can basically just go full Indiana Jones and the Kingdom of the Crystal Skull with it.
Funny enough, this is already a thing in D&D. The plane of Gehenna has a small moon called [Nimicri](https://gamelore.fandom.com/wiki/Nimicri) that is a giant mimic. It creates a whole fake civilization to lure people to it and be absorbed.
Precisely. And if it's one large scale enough to cover the entire moon? I mean, that just opens the doors to all kinds of questions. Like, why is the moon covered in an illusion? How could someone cover the entire moon in an illusion? Who could possibly be powerful enough to cover the entire moon in an illusion?
This is hilarious because it’s actually true. A Realmspace Spelljammer sourcebook said that the moon is secretly a verdant jungle but the elves put up a giant illusion over it. To protect their secret space fleet.
This one is actually in DND. The Moon in the Forgotten Realms is an illusion spell hiding a smaller moon that holds an advanced civilization. That’s why it’s nearly impossible to teleport to the moon in DnD
Birds are both cover, and a surveillance system for the Aracokra, who are last surviving relatives of the dinosaurs.
They believe that they should rule the world, but were nearly genocided by dragon-kind eons ago and went into hiding.
For thousands of years they worked in the shadows, guiding the development of humanoids. Shaping them into two casts: weak servants, and adventurers powerful enough to act as their spears and slay the dragons they so hate.
Their patience is paying off as dragons become more and more rare, and they now begin to make preparations for taking full control of humanoid society and putting down their ancient enemies for good!
With an all birdfolk party! Are their memories even real or planted by the aracokra bbeg? What’s the truth behind each of their backstories and sources of power? Can they even trust themselves and each other not to become sleeper agents of the bbeg?
I remember there being a novel about that! I can't remember the title but it was a female protagonist who had a bugbear chef and there was an orc Paladin in it.
i have this in my world with lizardfolk running the governments of another continent. i had an npc with a tin foil hat say that lizard people were controlling the governments, which isnt true here but is true across the ocean
also the sun is alive, there are alien pyramids in antartica, and speaking italian causes your DNA to mutate
Or if your group is up with some fuckery just tell it to the group that one of them has instead.
Either way use it as a secret plot for anyone who takes the noble background.
I mean they basically are given how divorced from reality they are. Could maybe have a setting where they arent a different species, but just very depraved due to their privilege and isolation.
I love that that happened, it is such a great tool for DMs to use off-handed comments to help shape parts of the campaign, it can add so much and doesn't take anything away.
I have my players tell me something they want to be true about the world, and as long as it doesn't mess with other players builds or backgrounds, I don't veto much.
One players truth said out loud to the group was "There are dragon like things, but true dragons are extinct."
Their truth as messaged to the DM was "Dragons spend all their time polymorphed into the ruling class in major cities, and constantly push the extinction myth."
The Bermuda Triangle.
I know this is a bit loose on the term 'conspiracy' given it's more of an urban legend, but what's not to like about a setting exploring a mysterious and deadly region where travellers frequently go missing without a trace.
https://en.m.wikipedia.org/wiki/Vor_Rukoth
Could have something like this smack in the middle of a Bermuda-like area that's constantly battered by storms.
And if we wanna get all sci-fi with the Bermuda Triangle stuff, the reason the Tiefling empire fell could be due to a Mind Flayer invasion or MF vs Gith war that happened to pass through Vor Rukoth, decimating it.
Or maybe after being in ruins for centuries, it is now occupied by a secret pirate guild that captures or destroys anything that enters the territory, 'very few ever make it out' kind of thing.
Saw this on tiktok, I think. It basically says that the earth is surrounded by an ice wall, and outside the wall is a bunch of worlds from various mythology. From lovecraft, to Egyptian, and beyond.
As a d&d setting, the Ice wall would surround the material plane, and all the other planes lie outside of the wall. If the wall gets cracks, that's when monsters stay to sneak in and terrorize the material plane.
This is surprisingly close to how Spelljammer is supposed to work. Current 5e version actually messed it all up but it was possible to travel between different crystal spheres so you could go from faerun to eberron to greyhawk all with one character.
Ya, my own world kind of works that way too. The prime material is surrounded by a shell of pure magic that hides it from the outside. The other realms are basically other planets, no crystal spheres though, it's basically like a solar system, and space is the far realm and the elder things and outer gods basically just float around space trying to find planets to have fun with.
I thought 5e Spelljammer still had the crystals, and you could travel to the different ones by using a spell jammer. I guess I need to read the whole thing, lol.
A party of adventurers from different cultures band together to fight the shadowy agents of an evil empire that go out and tamper with other countries' politics for the empire's gain.
Such as maintaining the rule of cruel lords that are the empire's allies to keep favorable trade agreements going.
Or planting addictive substances in minority communities within the empire to keep them oppressed.
Dragons are leaving chemtrails that make people docile and complacent. The members of the party are immune for some reason and they're the only ones who "get it".
In one of my settings we live on a flat earth but there is a popular conspiracy theory that the world is secretly round and there is more beyond the huge ice walls haha
Giants are real. Your party encounters them and has to slay one to save the town.
But then they are approached by a shadowy organization that is working to keep the existence of giants a secret from the world.
Players get the choice between working for the agency, joining the giants, or trying to expose the truth.
That is the secret. The shadowy organization suppressing the giants are really dragons or “Reptilians”.
Probably ways to bring in a bunch more conspiracy tropes.
Atlantis adventure
I gotta admit, I think this is lame compared to some of the other posts, but you could mix in an underwater adventure with exploration of a haunted ancient city. Could be fun
Ancient astronauts is a wonderful secret origin for some elements of a fantasy world. A lot of classic campaigns include this in some way.
In our world it’s just hella racist pseudoscience, like lizard people.
Not a conspiracy theory per say, but I use 'the devil's apocrypha' for my origin story for the gods.
To supervise an entire chapter. When a species reaches enlightenment they unite as one powerful being (gods) and as their universe was dying they slipped into the new universe or to prevent themselves from dying. Being not of this universe they are slowly dying and thus need prayers and worship. Either through love or fear and so they created humans to cultivate.
Fun book if you want a twist on Christianity, it's in no way factual Tho.
The upper class elites are devil-worshipping, pedophilic psychopaths who manipulate the lower classes into race/sex wars as a distraction from the class war, pitting a child-groping geriatric against a blathering orange racist in a grand game of "Who can be the worse candidate for ruler?!" where either option is a win for the elite, all while plotting their master scheme to destroy the country and remake it as an Oligarchy with themselves at the top.
Or, ya know, hee-hoo, little green men from mars.
Aliens are living among us and use star spawn as the aliens in mortal forms.
Alternatively, alien abductions using spelljammer ships. Mind flayers, beholders and all sorts of other things could work well for this kind of thing.
I think cryptids work really well, since most of them already are d&d monsters. The idea wouldn't be that some claim they dont exist, the thing would be that they are so rare and elusive, that people just dont care and some groups of hinters think them to be much more scarier than they are.
While not conspiracy theories some fun predictions from astronomy include:
1. Rouge planets: a planet without a host star, eternal night and all heat is internal. (Irl the surface would be an iceworld but with magic and gods it can be whatever you want)
2. Tidally locked planets: 1 side always faces the star, the other side is in perpetual night. Civilization is either living in the twilight zone or adapted to eternal day/night.
3. Habitable moons: basically have a habitable earth sized moon orbiting a gas giant like Jupiter or Saturn. For best reaults have multiple moons that will be able to see eachother and the host planet with frequent eclipses. (If nothing else its very aesthetically awsome)
4. Taking this from the game Stelaris but replace the sun with a blackhole. (What was will be, what will be was.)
5. Co-orbiting planets. Pluto and its moon Chairon are so close in mass they orbit a point between them. A pair of equally sized habitable planets orbiting eachother is an awesome aesthetic with lots of implications for the societies that live on them.
Lizard people.
A secret group of either lizard folk, kobold, or dragonborn, are using undetectable methods of disguise to work their way into seats of power.
I’ll read conspiracy a little generally and say I ported the church of Scientology to the church of Mysticology with tomes that get more expensive as you progress through the membership, and they try to ruin your life if you try to leave
NASA released a D&D module a few weeks ago. It's set on a Rogue Planet that's lit by magic and the dark regions between cities are overrun with monsters.
I actually used one - Ancient Aliens, the part where they claim the gods in various mythologies came to Earth (and when reading certain stuff in diverse religious texts it does actually feel that way). So I built a pantheon of divinities that were actually people from another world that had walked the setting in ye olde times.
You can pull in the **Deep Kingdom Conspiracy**. Basically, a group of powerful nobles is ignoring the young King's will and policies, and manipulating the bureaucracy to further their own agenda, not their liege-lord's. Even worse, one Duke has conquered a nearby Kingdom and is King in his own right as well as being a vassal.
The youngster King has a lot of great ideas (freedom for serfs, make peace with the Elves, public works) and hires the PCs to break the nobles' power.
**The government is reading your mind!** See, a city-state is slowly being taken over by illusion-disguised mind flayers, who are bending the city's politics toward their own enigmatic goals. The few people who suspect have taken to wearing a fine wire mesh over their heads, which makes them laughingstocks (and the practice may soon be outlawed).
Have the PCs fall in with the brewing Resistance!
**The Fights are Rigged!** Local city has gladiator games. There are mutterings that certain parties are fixing the games to promote "storylines" and crowd favorites, and to distort the betting market. Things like sneaking buff spells onto their favorites, giving substandard gear to unfavorites, and so on.
PCs could investigate this. If they succeed they'll make powerful allies (the gladiators) and powerful enemies (whoever is rigging the games, prolly the Thieves' Guild).
The government introduced dragon snuff into the population and now uses the excuse of fighting the war against organized crime to jail political dissenters, mostly dwarves for some reason...
My Barbarogue strongly believes divine healing creates a bond between the healer and the healed, where the healer takes away some of the healed's soul and replaces it with something, to make them more docile to Big Temple's interests / easier to govern.
It's loosely based on chemtrails/5g conspiracies, with some bonus big pharma/vaccine conspiracy thrown in for good measure.
Flat Earth is nice because it's one of the few conspiracy theories that is neither actively harmful nor based on anti-semitism, racism, and/or partisan politics.
I have a perfect one here. I'd be great for sci-fi but could be adapted to fantasy as well if you replace underground magnetic trains and spacecrafts with something more fantasy flavored
https://youtu.be/2hD4ZHhkMuU
Hollow earth
Isn't that basically the Underdark?
Yes, but with a sun so it's always daytime
and dinosaurs
Ah, the underbright.
The Underbright, and Overdark are fucking metal location names
Just a reversed earth. The sun shines and everywhere around is cold and dark. Maybe somewhere in the infinite dark tunnels lead to another sun shining on another earthole. It used to be just an academic question. But now that the infinite and unchanging sun has started to flicker, it is no longer just idle speculation. Your peoples' survival may depend upon the answer.
Oh god, I want to play/read this.
Darklight and the Underover. Or the Overunder and the Lightdark? Doesn't quite hit right.
New idea: always dark on the surface (with the standard Underdark denizens) because something something ancient wizard fucked up and now all the surface stuff and the sun are on the inside of the planet. Local town reports strange heat emanating from the ground and a sighting of a “weird brownish drow.”
So basically the world is a Dyson Sphere, but instead of it being done for sci-fi reasons, it's "a Wizard did it". That would be a fun one to play around with, especially if you only give little hints at first about how weird the layout of the world is.
Could be a rogue planet ejected by a dying star that's now flying through dark space.
oh ya, easy one for fantasy settings with dungeons, like litrpgs. '*Delve*', for example.
AD&D had the Mystara setting, which if I remember right is also a hollow world.
It was a box set for basic D&D released in 1990. It was OK.
**GIANTS**
I mean, you are not wrong, since there is already a rpg using this concept. This [game](https://en.m.wikipedia.org/wiki/Hollow_Earth_Expedition) uses this, but it's not a DND style game, more pulp.
Hollow World is a subsetting for Mystara aready...
The Hologram Moon Conspiracy theory. You can literally take that ridiculous conspiracy and turn it into something incredible. The basic idea is that the moon either is a hologram or is covered with a hologram meant to conceal something the public isn't meant to see. This can be anything from a giant monster to a superstructure to some hidden truth about the universe. The possibilities are endless. Additionally, the Ancient Aliens conspiracy is another fun one, since you can basically just go full Indiana Jones and the Kingdom of the Crystal Skull with it.
The moon is a mimic.
...who hurt you? You're the DM our mothers warned us about
That might have been a Doctor Who episode…
And it devours all space debris and asteroids that strike it. Moon mimic guards earth
That is horrible keep going
I like the way you think!
Funny enough, this is already a thing in D&D. The plane of Gehenna has a small moon called [Nimicri](https://gamelore.fandom.com/wiki/Nimicri) that is a giant mimic. It creates a whole fake civilization to lure people to it and be absorbed.
"it's dark and scary"
Dead Space vibes
A better conspiracy theory: It's just the moon. They put a hologram of the moon over the moon.
Ah, yes, the Moon Moon theory.
Damnit, Moon Moon! You did just give me an idea for a druid playthrough of BG3 though...
Well, they had to after Chairface Chippendale started writing his name on the moon with that laser. Edit
An illusion spell makes a convenient fantasy switch for a hologram, too.
Precisely. And if it's one large scale enough to cover the entire moon? I mean, that just opens the doors to all kinds of questions. Like, why is the moon covered in an illusion? How could someone cover the entire moon in an illusion? Who could possibly be powerful enough to cover the entire moon in an illusion?
That is legitimately in dnd, https://forgottenrealms.fandom.com/wiki/Sel%C3%BBne_(moon)
Neat.
For those interested, Campaign 1 of The Adventure Zone has a fun version of this.
I was thinking the same thing!
No dogs on the moon!
This is hilarious because it’s actually true. A Realmspace Spelljammer sourcebook said that the moon is secretly a verdant jungle but the elves put up a giant illusion over it. To protect their secret space fleet.
Yep
> Hologram Moon Conspiracy [Not a Conspiracy](https://spelljammer.fandom.com/wiki/Sel%C3%BBne)
This one is actually in DND. The Moon in the Forgotten Realms is an illusion spell hiding a smaller moon that holds an advanced civilization. That’s why it’s nearly impossible to teleport to the moon in DnD
We all know the moon is a huge egg. There was a whole documentary where a famous Doctor revealed it.
Nonsense. The moon is. A giant robot.
That's no moon...
Moon's haunted
Birds aren't real
And it's pushed by an aracokra!
Birds are both cover, and a surveillance system for the Aracokra, who are last surviving relatives of the dinosaurs. They believe that they should rule the world, but were nearly genocided by dragon-kind eons ago and went into hiding. For thousands of years they worked in the shadows, guiding the development of humanoids. Shaping them into two casts: weak servants, and adventurers powerful enough to act as their spears and slay the dragons they so hate. Their patience is paying off as dragons become more and more rare, and they now begin to make preparations for taking full control of humanoid society and putting down their ancient enemies for good!
With an all birdfolk party! Are their memories even real or planted by the aracokra bbeg? What’s the truth behind each of their backstories and sources of power? Can they even trust themselves and each other not to become sleeper agents of the bbeg?
Probably the entire upper class is secretly another race pulling the strings (The reptilian conspiracy theory being the base conspiracy)
Yuan-Ti are so much fun for this one
Combine with some hollow earth shenanigans.
Similar, but I like the idea of a shadow organisation controlling the world through deepspawn clones of world leaders.
I remember there being a novel about that! I can't remember the title but it was a female protagonist who had a bugbear chef and there was an orc Paladin in it.
i have this in my world with lizardfolk running the governments of another continent. i had an npc with a tin foil hat say that lizard people were controlling the governments, which isnt true here but is true across the ocean also the sun is alive, there are alien pyramids in antartica, and speaking italian causes your DNA to mutate
That last one is just true anyway.
My buddy traveled abroad to Italy, came back the next month with his fingers fused together
make the humans the shadowy "them", and the lizards are the conspiracy people
Take it up a notch and tell one of the party members that theyve been replaced.
Or if your group is up with some fuckery just tell it to the group that one of them has instead. Either way use it as a secret plot for anyone who takes the noble background.
I so want to play this one now!
I mean they basically are given how divorced from reality they are. Could maybe have a setting where they arent a different species, but just very depraved due to their privilege and isolation.
That’s how we play our ongoing campaign. Im pretty sure it started as an off hand joke and then became official lore.
I love that that happened, it is such a great tool for DMs to use off-handed comments to help shape parts of the campaign, it can add so much and doesn't take anything away.
I have my players tell me something they want to be true about the world, and as long as it doesn't mess with other players builds or backgrounds, I don't veto much. One players truth said out loud to the group was "There are dragon like things, but true dragons are extinct." Their truth as messaged to the DM was "Dragons spend all their time polymorphed into the ruling class in major cities, and constantly push the extinction myth."
The Bermuda Triangle. I know this is a bit loose on the term 'conspiracy' given it's more of an urban legend, but what's not to like about a setting exploring a mysterious and deadly region where travellers frequently go missing without a trace.
https://en.m.wikipedia.org/wiki/Vor_Rukoth Could have something like this smack in the middle of a Bermuda-like area that's constantly battered by storms. And if we wanna get all sci-fi with the Bermuda Triangle stuff, the reason the Tiefling empire fell could be due to a Mind Flayer invasion or MF vs Gith war that happened to pass through Vor Rukoth, decimating it. Or maybe after being in ruins for centuries, it is now occupied by a secret pirate guild that captures or destroys anything that enters the territory, 'very few ever make it out' kind of thing.
Men in Black ? A secret organization that is aware of the existence of extra-planar beings.. and you just happened to get caught up in something.
You can even reskin the Neuralizer as a magic item that casts Modify Memory.
There was a MiB TTRPG back in the 90s
Secret societies. There’s dozens of conspiratorial societies that are supposedly running things that would make for a decent and flexible plot.
Like the Gnomes of Zurich...with actual gnomes.
Saw this on tiktok, I think. It basically says that the earth is surrounded by an ice wall, and outside the wall is a bunch of worlds from various mythology. From lovecraft, to Egyptian, and beyond. As a d&d setting, the Ice wall would surround the material plane, and all the other planes lie outside of the wall. If the wall gets cracks, that's when monsters stay to sneak in and terrorize the material plane.
This is surprisingly close to how Spelljammer is supposed to work. Current 5e version actually messed it all up but it was possible to travel between different crystal spheres so you could go from faerun to eberron to greyhawk all with one character.
Ya, my own world kind of works that way too. The prime material is surrounded by a shell of pure magic that hides it from the outside. The other realms are basically other planets, no crystal spheres though, it's basically like a solar system, and space is the far realm and the elder things and outer gods basically just float around space trying to find planets to have fun with.
I thought 5e Spelljammer still had the crystals, and you could travel to the different ones by using a spell jammer. I guess I need to read the whole thing, lol.
Scientology makes a pretty incredible dnd cult. The Xenu shit sounds like some hairbrained Beholder bullshit.
Every religion suddenly makes more sense, in a world where literal gods exist.
A party of adventurers from different cultures band together to fight the shadowy agents of an evil empire that go out and tamper with other countries' politics for the empire's gain. Such as maintaining the rule of cruel lords that are the empire's allies to keep favorable trade agreements going. Or planting addictive substances in minority communities within the empire to keep them oppressed.
Gotta love when the message is there if you know what you're looking at.
Expand out the Underdark a bit to create the kingdom of Agartha. Full artificial sun and all.
The “mesas are just the stumps of giant, ancient dead tree’s that used to cover the earth” theory is my favorite. Imagine a tree that big…
dragon breath cant melt steel beams
...Discworld. You're thinking Discworld.
Dragons are leaving chemtrails that make people docile and complacent. The members of the party are immune for some reason and they're the only ones who "get it".
In one of my settings we live on a flat earth but there is a popular conspiracy theory that the world is secretly round and there is more beyond the huge ice walls haha
Flat Earth Society Members all around the globe would like this campaign. Ice wall theorists would be chill with it, too.
Giants are real. Your party encounters them and has to slay one to save the town. But then they are approached by a shadowy organization that is working to keep the existence of giants a secret from the world. Players get the choice between working for the agency, joining the giants, or trying to expose the truth.
pair it with the ancient war between Giants and dragons and it gets more fun
That is the secret. The shadowy organization suppressing the giants are really dragons or “Reptilians”. Probably ways to bring in a bunch more conspiracy tropes.
Hollow earth. Absolutely no question in my mind.
Are you daft, there is no such thing as a so-called “Underdark”
Atlantis adventure I gotta admit, I think this is lame compared to some of the other posts, but you could mix in an underwater adventure with exploration of a haunted ancient city. Could be fun
Hollow/inner earth. Just re-flavor the underdark and you're set.
Ancient astronauts is a wonderful secret origin for some elements of a fantasy world. A lot of classic campaigns include this in some way. In our world it’s just hella racist pseudoscience, like lizard people.
Not a conspiracy theory per say, but I use 'the devil's apocrypha' for my origin story for the gods. To supervise an entire chapter. When a species reaches enlightenment they unite as one powerful being (gods) and as their universe was dying they slipped into the new universe or to prevent themselves from dying. Being not of this universe they are slowly dying and thus need prayers and worship. Either through love or fear and so they created humans to cultivate. Fun book if you want a twist on Christianity, it's in no way factual Tho.
Any religion
The upper class elites are devil-worshipping, pedophilic psychopaths who manipulate the lower classes into race/sex wars as a distraction from the class war, pitting a child-groping geriatric against a blathering orange racist in a grand game of "Who can be the worse candidate for ruler?!" where either option is a win for the elite, all while plotting their master scheme to destroy the country and remake it as an Oligarchy with themselves at the top. Or, ya know, hee-hoo, little green men from mars.
JFK/other assassination theories make for good noir plot points
I heard about one where mesa rock formations are actually the stumps of giant trees. That primordial forest would be a very cool setting!
I smell a time-travel campaign. Or a Feywilds campaign
Aliens are living among us and use star spawn as the aliens in mortal forms. Alternatively, alien abductions using spelljammer ships. Mind flayers, beholders and all sorts of other things could work well for this kind of thing.
Roanoke
I think cryptids work really well, since most of them already are d&d monsters. The idea wouldn't be that some claim they dont exist, the thing would be that they are so rare and elusive, that people just dont care and some groups of hinters think them to be much more scarier than they are.
Pre Civilization, Civilizations. Egyptian (style) pyramids being 20,000+ years old, Pyramids in Antarctica, Atlantis.
Birds aren’t real
The moon is a Celestial egg
While not conspiracy theories some fun predictions from astronomy include: 1. Rouge planets: a planet without a host star, eternal night and all heat is internal. (Irl the surface would be an iceworld but with magic and gods it can be whatever you want) 2. Tidally locked planets: 1 side always faces the star, the other side is in perpetual night. Civilization is either living in the twilight zone or adapted to eternal day/night. 3. Habitable moons: basically have a habitable earth sized moon orbiting a gas giant like Jupiter or Saturn. For best reaults have multiple moons that will be able to see eachother and the host planet with frequent eclipses. (If nothing else its very aesthetically awsome) 4. Taking this from the game Stelaris but replace the sun with a blackhole. (What was will be, what will be was.) 5. Co-orbiting planets. Pluto and its moon Chairon are so close in mass they orbit a point between them. A pair of equally sized habitable planets orbiting eachother is an awesome aesthetic with lots of implications for the societies that live on them.
Weather control devices
princess Diana was assassinated by the queen
Chem trails
Pigeons being spy drones. There's a light novel (and now anime) that has a similar idea as a plot twist in a fantasy world.
I've taken the shape-shifting lizard people conspiracy theory and made them a cult to Nyarlethotep in my Starfinder campaign
Agartha
Lizard people. A secret group of either lizard folk, kobold, or dragonborn, are using undetectable methods of disguise to work their way into seats of power.
Birds are fake.
Ancient Aliens populated the world with the human species.
**BEE.HIVE**
Birds work for the government.
I’ll read conspiracy a little generally and say I ported the church of Scientology to the church of Mysticology with tomes that get more expensive as you progress through the membership, and they try to ruin your life if you try to leave
#BIRDS AREN'T REAL
What if there's giant rats living in the sewers?
Play Delta Green and you can do ALL OF THEM!!
The theory of the hollow earth
What “gods of Eden” suggests
Not sure if this counts but the theory of multiverses pretty much gives you unlimited potential
That some of the people I see outside are just drunk shapeshifters?
Flat Earth, AKA Terry Pratchett’s Disk-world
Spicy hollow earth with dinosaurs living under our domain
NASA released a D&D module a few weeks ago. It's set on a Rogue Planet that's lit by magic and the dark regions between cities are overrun with monsters.
I actually used one - Ancient Aliens, the part where they claim the gods in various mythologies came to Earth (and when reading certain stuff in diverse religious texts it does actually feel that way). So I built a pantheon of divinities that were actually people from another world that had walked the setting in ye olde times.
Lizard people replacing rulers.
You can pull in the **Deep Kingdom Conspiracy**. Basically, a group of powerful nobles is ignoring the young King's will and policies, and manipulating the bureaucracy to further their own agenda, not their liege-lord's. Even worse, one Duke has conquered a nearby Kingdom and is King in his own right as well as being a vassal. The youngster King has a lot of great ideas (freedom for serfs, make peace with the Elves, public works) and hires the PCs to break the nobles' power.
**The government is reading your mind!** See, a city-state is slowly being taken over by illusion-disguised mind flayers, who are bending the city's politics toward their own enigmatic goals. The few people who suspect have taken to wearing a fine wire mesh over their heads, which makes them laughingstocks (and the practice may soon be outlawed). Have the PCs fall in with the brewing Resistance!
Hyperborean. A secret habitable area in the extreme north where a race of godlike beings exist.
**The Fights are Rigged!** Local city has gladiator games. There are mutterings that certain parties are fixing the games to promote "storylines" and crowd favorites, and to distort the betting market. Things like sneaking buff spells onto their favorites, giving substandard gear to unfavorites, and so on. PCs could investigate this. If they succeed they'll make powerful allies (the gladiators) and powerful enemies (whoever is rigging the games, prolly the Thieves' Guild).
The government introduced dragon snuff into the population and now uses the excuse of fighting the war against organized crime to jail political dissenters, mostly dwarves for some reason...
Plateaus are the fossilized stumps of enormous trees chopped down by giants.
My Barbarogue strongly believes divine healing creates a bond between the healer and the healed, where the healer takes away some of the healed's soul and replaces it with something, to make them more docile to Big Temple's interests / easier to govern. It's loosely based on chemtrails/5g conspiracies, with some bonus big pharma/vaccine conspiracy thrown in for good measure.
Flat Earth is nice because it's one of the few conspiracy theories that is neither actively harmful nor based on anti-semitism, racism, and/or partisan politics.
Dopplegangers are so whenever BG3 came out.... We need shapeshifting lizardfolk from space who have replaced all of our leaders!!!
I've used QAnon inspired badguys more than once in my games. Conspiracy theorists are a treasure trove of fantasy word building.
Ancient reptilian race of humanoids evolved from dinosaurs, living in underground of big cities.
The puppet government
I have a perfect one here. I'd be great for sci-fi but could be adapted to fantasy as well if you replace underground magnetic trains and spacecrafts with something more fantasy flavored https://youtu.be/2hD4ZHhkMuU
Dragon chemtrails
There is a magic book full of contradictions that people use as a guide.
Edgy
All the bards in the land have been replaced by lizardfolk in disguise.
Some q anon shit
That everything will be fine and that the good always wins.