Weird Worldbuilding

Building off KoldikSteelskin's post on how we make these worlds to play in, I've got another curiosity.

What's the weirdest piece of lore you've created?

On purpose or on the fly, all are welcome here.

My personal favorite was in a short-run Humblewood game, which is a 5e setting somewhat inspired by Redwall. Everyone's a human-sized woodland creature.

We were wondering about livestock, and I decided giant spiders would make great horses, since insects are a step down from animals in a way. And then because I thought it would be adorable, I decided the cow-equivalents were GIANT bumblebees, still providing meat, labor, and hide. And since the idea of cow-sized bees ravaging a flower field is unsettling, we let normal bees exist too, which is kinda like how normal D&D has both Tabaxi and cats.

What are your favorites?

I created a race of snake people for a world who revered their prominent dead ancestors by preserving their skins and wearing them much like a wolf-were dons the skin of a wolf. While wearing these skin-suits, the snake-person inside, takes on aspects of their deceased ancestor.

Woah. Spooky, but also really neat!

I used an old tried and true method for getting a party together - you are invited to the reading of a will.

During the will reading, I throw out this idea that there is this problem called Gravedust, a kind of magical storm that kills all people -- not animals or birds, just people. This idea spawned two lengthy campaigns.

The first party were all evil (a rogue, a necromancer, and a divine soul which is like a cleric), and ended up working for a wizard who called himself Manbane, who was trying to create a better 'human' in order to survive a coming Titan invasion. The Titans had already conquered (or in the case of one, destroyed) the other six of the seven ring-shaped planets in the strange system. In the campaign, the wizard assassinated and replaced the Orcish greater god in the pantheon, and the party became all but demi-gods in his service.

The second campaign came about in a shadowy, mist-cloaked demi-world after the first world was shattered at the end of the first campaign (which was a quirky defensive action). The first party were immortal NPCs the second party ran into in the first pocket realm they traveled to through the strange, mystical mist that connected scores of such pockets in the magical vaporous remnants of the destroyed world.

Awesome. I love when worlds can handle two connected campaigns.

The greatest piece of "lore" that me and my group came up with on the fly, was all because of a misunderstanding.

In my current Lost Mines of Phandelver campaign, the players were just entering Phandalin for the first time. I (the DM) mentioned to the group that there was a building with a sign that said, Bart's Bar and General Goods. Pretty average name, nothing fancy. But one of my players excitedly but confusedly responded, "Bart's Drag Bar?!?!" I smirked and I was about to correct them, and one of the other players was about to as well, but I decided to roll with it.

So, now Phandalin, this little frontier town nestled deep in the Sword Mountains, is proudly home to a biweekly drag show which attracts tourists and drag queen adventurers alike from all up and down the Sword Coast. The guy who owns the shop, Bartholomew and his cat familiar Bartholomeow, put on a stunning performance ever time, using magic to create music and light shows. Some of the most popular drag queens that perform there include Misty Step, Wild Shapira, Pact Bonnie, and Hellish Rebekka (all named after my players' spells and abilities).

And when the Redbrand Ruffians showed up in the middle of Scorching Raya's performance to shut it all down, hurling profanities and destroying the stage, I can tell you that my players needed absolutely no other motivation to completely drive the Ruffians out of town (a nice way of saying absolutely eradicating them from existence).

That’s brilliant! I’m adding that to my Phandalins now. Accidental lore is the best lore.

My favourite accidental lore from GP is that kobolds are superb pastry chefs. Thanks to the IDRotF party, in the 1490s DR there is an aggressively expansionist fast-food patisserie empire sweeping across Faerun headed by Ray Croc.

I think the best accidental I've run into is the Elvis-impersonating elf mummy who croons at the aforementioned patisserie.

I've got some weird lore, but I haven't dropped it on players yet, so I don't want to spoil anything.

Brilliant!

Yeah. I think I've seen this guy before and an undead orc named Cash too.

These are delightful!

Not as much weird lore as weird mechanic. At the home owner's place if their cat hopped up on the poker table and walked towards them they all got a Bennie (game was in Savage Worlds), if it walked up towards me I'd roll random weirdness. No beckoning of the cat was allowed.

Usually mid conversation in a scene cat would always hope up on the table sometime look at the players and walk over and but most of the time they would sit in front of me and stare at them and purr. With the Co-GM Cat suggestions I rolled randomly and it became themed, one player lost thirty minutes while talking frozen in place, another they PCs were eating breakfast in the cafeteria and everyone around them vanished so they moved about until getting to the quad. No sound besides themselves, no insects, later in the quad everyone showed back up in a blink of an eye with sound, so odd fifteen minutes they were timing it, time moved back to when they were the cafeteria and they were outside though weirdness instantly. Another one was having a conversation the cat jumping up and rolling over on my books in front of me and me selecting and laughing before I restarted the scene over with a shrug before they asked "you know you already said this right" with the reply "yep and you're players do too." got them looking at the creepy time cat on the table since it was random but suspicious.

If it's player invented lore someone came up for with (All new players that hadn't played at RPGs before) the US was in Spain for the alleged dragon that the PC were on assignment to find for their organization but hadn't found yet. The US needed the dragon because the current president after Obama wanted it to attack countries with and be able to then say it was imaginary and this attack was fake news. I gave her a Bennie since she was totally serious and immediate with a response, everyone got another glass of wine, my wife was still mad their contact on the ground was a guy in a wheelchair that looked like Jeff Bridges... Dragon ate his legs...
Forgot the others but they were time related with snippets lost to the cat.

In my current campaign, the PCs are just finishing a quest for the nine coins of morality. Each coin is tied to an alignment and gives specific powers to the wielder. Collect all of the good, neutral, or evil coins and you get another power, and collecting all the coins grants yet another power. Each coin is made of a specific material and is about three inches in diameter.

Coin of the Crusader - platinum - lawful good - while attuned:
* You are immune to disease
* You can cast globe of invulnerability; after casting roll a d6, on a 1-5, you cannot cast it again until the following dawn
* Your flaw is amplified in a way determined by the DM
* The artifact erases magical scrolls within 10 feet of it, rendering them non-magical

Coin of the Benefactor - gold - neutral good - while attuned:
* You can cast mass healing word; after casting roll a d6, on a 1-5 you cannot cast it again until the following dawn
* You can cast heal; after casting roll a d6, on a 1-5 you cannot cast it again until the following dawn
* Nonmagical flames are extinguished within 30 feet of you
* Creatures with a challenge rating of 0, as well as plants that aren't creatures, drop to 0 hit points when within 10 feet of the artifact

Coin of the Rebel - silver - chaotic good - while attuned:
* You can cast counterspell; after casting roll a d6, on a 1-5 you cannot cast it again until the following dawn
* You can cast scatter; after casting roll a d6, on a 1-5 you cannot cast it again until the following dawn
* While you are attuned to the artifact, animals within 30 feet of you are hostile toward you
* While you are attuned to the artifact, beast creatures are always hostile toward you

Coin of the Judge - brass - lawful neutral - while attuned:
* You can cast clairvoyance; after casting roll a d6, on a 1-5 you cannot cast it again until the following dawn
* You can cast true seeing; after casting roll a d6, on a 1-5 you cannot cast it again until the following dawn
* You have disadvantage on saving throws against spells
* When you become attuned to the artifact, one of your ability scores is reduced by 2 at random a greater restoration spell restores the ability to normal

Coin of the Undecided - tin - neutral - while attuned:
* You can use the coin as a wand of wonder with no chance of destruction; roll 1d6, on a 1-5, it cannot be used again until the following dawn
* You can cast mass suggestion; after casting roll1 d6, on a 1-5 you cannot cast it again until the following dawn
* Your weight increases by 1d4 × 10 pounds
* You determine your alignment daily at dawn by rolling a d6 twice. On the first roll, a 1-2 indicates lawful, 3-4 neutral, and 5-6 chaotic. On the second roll, a 1-2 indicates good, 3-4 neutral, and 5-6 evil.

Coin of the Free Spirit - copper - chaotic neutral - while attuned:
* You can't be frightened or charmed
* You add 2 points to your Wisdom score (max. 24)
* You are blinded when you are more than 10 feet away from it
* The artifact dilutes magic potions within 10 feet of it, rendering them nonmagical

Coin of the Dominator - iron - lawful evil - while attuned:
* You can cast fast friends; after casting, roll a d6, on a roll of 1-5, you cannot cast it again until the following dawn
* You add 2 points to your Charisma score (max. 24)
* Other creatures can't take short or long rests while within 300 feet of you
* The artifact dilutes magic potions within 10 feet of it, rendering them nonmagical

Coin of the Malefactor - steel - neutral evil - while attuned:
* You can cast animate dead; after casting roll a d6, on a roll of 1-5, you cannot cast it again until the following dawn
* You can cast create undead; after casting roll a d6, on a roll of 1-5, you cannot cast it again until the following dawn
* You emit a sour stench noticeable from up to 10 feet away
* While you are attuned to the artifact, your body rots over the course of four days, after which the rotting stops. You lose your hair by the end of day 1, finger tips and toe tips by the end of day 2, lips and nose by the end of day 3, and ears by the end of day 4. A regenerate spell restores lost body parts.

Coin of the Destroyer - lead - chaotic evil - while attuned:
* You can cast fireball; after casting roll a d6, on a roll of 1-5, you cannot cast it again until the following dawn
* You can cast disintegrate; after casting roll a d6, on a roll of 1-5, you cannot cast it again until the following dawn
* The first time you touch a gem or piece of jewelry while attuned to this artifact, the value of the gem or jewelry is reduced by half
* Before you can become attuned to the artifact, you must kill a creature of your alignment

With all of the good-aligned coins, while attuned to the artifacts (and you must be attuned to all three), you can't be blinded, deafened, petrified, or stunned.
With all of the neutral-aligned coins, when you hit with a weapon attack while attuned to the artifacts (and you must be attuned to all three), the target takes an extra 1d6 damage of the weapon's type.
With all of the evil-aligned coins, while attuned to the artifacts (and you must be attuned to all three), your Strength score increases by 2, to a maximum of 24.

With all nine of the coins, you can cast gate. After casting, roll 1d6. Ona 1-5, you cannot cast it again until the following dawn. In order to do this, you must be attuned to no fewer than one of each type (good, neutral, evil) coin. Also, when you become attuned to the artifacts, you gain a form of long-term madness.

To destroy them, all of the coins must be thrown into the volcano Krakytos on Nessus, the 9th layer of Hell.

I love the cat mechanic. (Me-cat-nic?)

With the coins do they always get madness, or o ly when attuned to conflicting alignments?

In my original write-up, the madness always takes hold. Now, you could easily say that the detrimental effects only affect those not of the alignment of the coin in question, but this doesn't address the madness issue (but this only applies if all nine coins are owned and the individual is attuned to three coins, each of a different ethos (good, neutral, and evil)). Note that the person doing the attunement does not have to hold all nine coins; it is enough for them to be in close proximity, say 30 feet or so.

What is the logic behind the Neutral Good coin having a passive ability that turns you into a walking slaugterhouse and ecological disaster?

It's just a plot device so the characters have to fight Greta Thunberg.

Though... if you were a fireman the critters would be dead anyway and you'd be saving the planet...

I admit that I could have put more thought into the drawbacks for some of these, but that seemed to go well with the healing ability that you would effectively kill plants and small animals around you.