Death of an Idea: What else may have happened? And how did the planet recover?

[Nagog]

I'm currently running 5e games in a low-magic setting that, millennia ago, had an apocalypse as a creature known as the Diriac "visited".

Backstory: The Diriac exists on the Plane of Dreams, which is a middling plane between the realms of Thought and Emotion (similar to the Feywild/Shadowfell being middling planes between Physical and Emotion and the Astral being between Physical and Thought), as such most entities would have no way to grasp it's existence. The Diriac itself is like a massive whale that feeds on ideas, concepts, and metaphysical stuff like that. Continuing the whale analogy, if the Diriac is a Whale, Gods and Magic (and concepts like Civilization, Society, and widely accepted ideas) are Krill. The mortal races are bacteria that benefit from the existence of Krill.

That said, when the Diriac visited this world, over the course of 3-5 years everything collapsed. Magic completely stopped functioning, Gods were suddenly forgotten as if they'd never existed, Dragons began rampaging as they lost their connections to their multiversal selves, and the magical races of the world began to panic and do terrible things in (most often vain) attempts to escape, including ritually sacrificing their own gods.

The less magical races (anything from Humans to Elves) suffered from complete societal collapse as concepts such as cooperation, community, and the like were magically wiped and barred from their minds.

In the few millennia since, the ideas of community and such regrew and reformed, and magic is slowly beginning to return as well, though the world as a whole remains isolated from the wide planescape.

What other events may have occurred during this apocalypse that I can allude to, or that may have lingering effects in the world today?

[Millstone85]

Shamelessly plagiarizing a SCP Foundation tale...

There could be monoliths and other structures that were formed during Diriac's passage and now remain mentally invisible to humanoids, not by Diriac's will but because humanoids developed a subconscious "see no evil" defense mechanism. Everyone actively avoids these places, including by building roads that go around them, yet nobody knows they exist.

The PC could somehow become aware of these places and set to explore them like dungeons. There they encounter various aberrations, including creatures that the mind will not register as human while simultaneously recognizing that it logically should. Correct number of eyes in the right place, same with the nose, the mouth, etc. yet less facelike than a rock with three holes around a bump. Correct number of fingers in the right disposition, yet less handlike than a branch.

[brian 333]

Memory Crystals: most are not worth the danger of consuming them. Most of the rest hold memories that apply to violent historical events, inventions that destroyed the people who used them, or other information that causes more harm than good. Some very few have information useful to a person, group, or society.

"Meymar is waking," he heard, as if in a dream.

Then he woke to a painfully intense white light: a single candle burned. He hoped that would go away; they had warned him of permanent disabling effects.

"Meymar," the elder asked, "Do you remember?"

"Yes," he said. Then, "Yes."

"Tell us your Memory!" the eager elder said.

"It was a Tuesday in July. There was a yellow flower in a field. I watched a bee drink it's nectar."

"Anything else?"

"That's it."

"What is a Tuesday? What is July?" the elder asked.

"What is a bee?" the first voice asked.

[sktarq]

Okay. Firstly I would say you could have a whole bunch of sub races, magical beasts etc as the idea of "Gnome" broke down and various splat versions show up. Which could have interesting social knock on effects

Also why would the ideas of cooperation and community get eaten but concepts like violence or hate not get the same treatment? How many just wander away?

Do some people try to get back to the sense of the creature's visit when concepts like hunger, social norms etc didn't weigh on them? What would they do break these ideas down again now that they suffer under their oppression?

What about lost words? When the idea reformed I'd imagine some people would remember the meaning that goes with the word but some words may have totally lost their meanings....and many others would have significantly shifted...most languages go through a serious shift. And even if you grew up with the old tongue you kinda have to re learn it when the ideas you are trying to communicate come back sometimes imperfectly. So all languages have an "old" and "new" versions and old texts don't really make much sense now and only general concepts...though perhaps some have touched some core idea and are now magic books (and can grant ability boons or something)...which means old spells or old scrolls etc may be unreliable (possible wild magic effects). Now a few millennia on languages have grown and shifted even more....and pre visit languages may need something special to even read...a spell or feat perhaps.


The unremembered. Some who have a clue what Dirac is are desperate for survival. If they are without an concept though they feel they may be protected. The practices of emptying ones mind leads to discovery of ki, but some go farther, some defy the world to even notice them...be it underground, or on a mystical level (like shadow creatures or skulks) or changlingswho gave up the idea of their identity to such and extent that there was no idea of them for Dirac to even try to eat...though those who tried and still were touched by the visitor were effected...some succeeded and became doppelganger but other took on some part of other identities...become fox people, or werewolves etc.
Other time places were forgotten. With no concept of havinf ever existed. Tiny bubbles of the old world. Much of modern society is built on people finding these forgotten places. Some still exist still lost to the new world. Still forgotten still safe....who knows what the old world wished to send to the new...but the brave seek them out. And some defend themselves by seeming to be something else...something that will defend them...and so they build it around them...or rebuild it after it has been raided...in common parlance these may misunderstood as living dungeons.

Also some concepts like "granite" shifted during the visit...mountains flowed...sometimes the concept of "down" failed and rivers or mountains flowed what we would today call "up" and the resulting spires, rubble piles etc still litter the land today.