Don't worry about the big monsters, legendary heroes, great wizards and such like; almost all of these were wiped out attempting to prevent the end of the world or during it. Maybe also 'retire' any PCs of greater than 6th level.
If you're going to play with humans and close-to-human characters, you can basically use RAW for whatever edition of whatever system you're using. Apply a bit of logic: characters will have either lived through the apocalypse, or it will have happened within recent living memory.
There's room for survivalist, out-of-the-ashes and assorted other zombie-apocalypse styled play. Or you can use the setting as the new normal; it doesn't have to be a grimdark, crapsack, misery crawl (but it can be if that's what you want).
Importantly, and based on AD&D, only 1st and 2nd level cleric spells are available; this is a godless universe. Scrolls are not affected, but you can't scribe the higher levels, nor use the scrolls to learn. Mythos priests may have totally lost their faith and powers.
If you want to, druids can get round this by teaming up with Dark Young, or through an extension of the druid vs. druid advancement rules in AD&D 1e.
All spells, unless cast inside a dungeon (or comparable adventure site), take longer to cast by one step (dependent on the rules you are running) and absolutely require material components. Dungeon casting is with the usual casting times and you may also choose to handwave components; Magic Users are keen to set-up shop in dungeons for this reason.
Ancient, anachronistic and alien equipment will crop up with greater regularity, and some common supplies may become rare to non-existent. The
Dark Sun and
Carcosa settings can provide rules and source material for this kind of stuff.
Characters should start out with better than normal hit points, either maximum possible or equal to their CON (until they gain enough HD to roll higher than this).
Mythos PCs.
I've already posted details for Deep One, Ghoul, Shoggoth and Yithian characters: these are not the originals for Stranger Aeons but will do for a start. Background details for the four playable types are as follows:
Deep Ones.
Sorry, my fishy chums. It turns out that the millennia of worship and breeding with dry-landers was for nothing; the glorious, ancient prophecies were not for you, either. The DNA-deep drive behind your civilisation turned out to be a cosmic lie.
While some of the Elders still cling to the old ways, surviving Deep Ones now live an amphibious, integrated existence with dry-landers. Adapting to life amongst dry-landers but not as their masters, you're no longer eating great quantities of raw meat, and size has diminished (though not as much as in The Shuttered Room).
Bereft of their gods, faith and certainty, religiously-minded Deep Ones are turning to the absent gods of the humans; they now prefer their gods to be at much greater than arm's length.
The ancient Guild of Coprophages, which previously consumed the feces of the Elders, continues its work in a new form, devouring the waste of the mixed communities. It's dirty, honest work.
Ghouls.
Ghouls were always closer to mortals than other mythos monsters, and it was both fairly easy and natural for them to step out of the shadows. People got used to them pretty quick, though they're not welcome round hospitals.
I always liked undead ghouls as much as Lovecraftian, so combine the two. They can be loyal, if unsentimental, companions, and can communicate with nightgaunts (no free pass through the Archipelago, though).
Shoggoths.
If using BECMI/RC, combine the following: green slime (B), black pudding (E), elemental (C), adaptor (M). Add Halfling advancement and saves. They regenerate 2 hp/round, except damage from ultraterrestrial sources.
STR and CON must be raised to 18 by lowering INT, WIS, DEX and CHA, 1 for 1. You could use the alignment drift of Athasian half-giants for Shoggoths if it's appropriate for your game.
Based on Mr. Shiny the Shoggoth Lord and Michael Shea's Fat Face (but less compulsively homicidal), Shoggoths have been living amongst mortals for countless centuries and have been growing somewhat like them as they have. Most have been maintaining a bulky humanoid form for years now.
Horribly overpowered at front-end, Shoggoths are probably the new masters of the earth and starting to realise it. Functionally immortal, they have no urgency to this end and like carrying out big civil engineering and landscaping projects in the middle of nowhere, as well as attempting to learn the finer points of mortal social behaviour. They can always just destroy things and absorb you if they get frustrated.
Yithians.
Yithians are pretty much as detailed in the earlier post; I just wanted to follow the model of four classes.
The Great Race are scholarly adventurers and 'death' is only a rude interruption that means they lose their place in the narrative. Aftermath of the Cthulhuvian apocalypse is just another day at the office for them.
Mix and Match.
There's no particular reason why you can't have regular characters and mythos characters in the same party; there's no reason they can't get along.
Obviously, the mythos classes are heavily front-loaded and unbalanced compared to the regulars. But that's the point.
Shoggoths are remarkably sensitive about assumptions of being used as pack mules, meat shields and battering rams, in spite of their considerable strengths in these areas. I suppose they don't like being stereotyped.
The Others.
The Mi Go/Fungi from Yuggoth and the Old Ones/Elder Things/Primordial Ones are the other two significant species to feature in Stranger Aeons.
Because I've always thought there was surprisingly little difference between Chthonians, Lloigor and Flying Polyps, we'll leave them out of it (this is another post, for the future).
Visitors from other worlds and dimensions do drop by; it's probably a bit easier for them to do so, but they're no more or less bothered about the mundane world than previously.
I also have a special place in my heart for good old pseudocanis Tindalosi, but I'll keep them back for another post, because I didn't adapt them for the setting until after the initial push.
Mi Go/Fungi from Yuggoth.
Cross a shrieker, giant bee and giant crayfish to get a statblock for an earthbound Mi Go. Give it human average or better INT. They're scientists, surgeons and miners, so their fighting styles, special abilities, equipment and behaviour will reflect this.
If you kill one, it will turn to stone, acid or explode like a Dragonlance Draconian; they never leave remains.
They're not working in secret anymore and will even let you wander round their bases as long as you don't interfere or try to access restricted areas. They don't like you, though, and their eerie buzzing makes you confused and sleepy. Do not fall asleep in or near a Mi Go base.
Give them weapons of a significantly higher technology level than the rest of the setting; they won't use anything as gross as gunpowder, though they still use blades, spikes and their little nippers.
Mi Go lairs are always bursting with mined and processed precious metals and gems, which they largely do not value (but know you do), just need to get out of the way while looking for rarer substances.
Ultraterrestrial Mi Go.
The earthbound Mi Go are the lesser representatives of a species from outside mundane space-time.
With the Great Old Ones gone, the ultraterrestrial Mi Go are incrementally slipping back in to take over the whole operation. They find mundane space-time unpleasant, even deleterious, so cannot remain here long; the ultraterrestrial Elder Things have a solution to this, but do not want to share.
Use a mind flayer as the basis for an ultraterrestrial Mi Go. Its brain eating ability is effective against all inhabitants of mundane space-time; it is a psychic/psionic power rather than a physical one. Use the nightshade from BECMI/RC for general immunities, touch and aura effects - the very presence of a Mi Go is poisonous to mundanes (earthbound Mi Go also suffer, but only at 50% intensity).
An ultraterrestrial Mi Go must consume one earthbound Mi Go for every hour it spends in mundane space-time or shift itself to another continuum (this could include other planes, but more likely their own dimension); earthbound Mi Go must always and absolutely obey their commands, no save.
Ultraterrestrial Mi Go are accompanied by a constant and discordant electronic/metallic screeching noise (the sound of them rubbing mundane space-time the wrong way), which causes nausea and bleeding in mortals.
The Old Ones (Ultraterrestrials).
As far as this world is concerned, the Old Ones died out without even the indignity of being dug up by polar explorers after millions of years. Those earthbound creators of all planetary life might get a post of their own sometime.
Abandoned cites and equipment exist; some will have been commandeered by Shoggoths. Perfectly preserved corpses still lie beneath the seas and polar ice, and who knows what has been brought closer to the surface by the transition of the Great Old Ones?
In Stranger Aeons, the original, ultraterrestrial Old Ones now have the opportunity to take back this little planet now it has been divested of Great Old Ones. To this end, they are converting mundane space-time into something more amenable to them (coincidentally, this is also suitable for Mi Go).
The Old Ones do not care to leave their preferred environment (which is why I never statted them; presume they are at least equals of the ultraterrestrial Mi Go). While unsympathetic to and uninterested in what happens in mundane space-time, they are not troublesome neighbours (except for the deadly poisonous aura) and are almost impossible to provoke (after all, what harm can you do?).
This doesn't mean anyone really likes living near an enclave/encroachment, but you might get used to it.
Shoggoths don't like getting too close to Old One encroachments, as they would be bound to absolutely obey any issued commands, no save.
What Else Is Going On?
The Dark Young.
Use a mash-up of BECMI/RC ghoul (B), treant and troll (E) (possibly throw in something that has a blood draining attack) as the basis for a Dark Young of Shub-Niggurath.
I decided the Dark Young were elemental extensions of the multiverse (dignifying Shub-Niggurath as some kind of 'real' deity, beyond all others). Give individual Young immunities and special abilities based on one of the D&D elements (including para- and quasi-).
While I never worked out the particulars, I thought druids should be able to tap them to power spells that were otherwise cut off.
Dark Young are still hostile monsters.
Weapon Masters.
If you're using the Weapon Mastery rules from BECMI/RC, there is only one Grand Master for each weapon, maybe up to three Masters, and to achieve relevant rank you must defeat (though not necessarily kill) them in one-on-one as well as the usual training time and cost. If you're that rank, prospects come after you, including PvP.
Guild/Union of Summoned Monsters.
Intelligent monsters subject to summoning spells now tend to congregate in and around dungeons, forming mixed communities as members of the Guild/Union. Being summoned is not a pleasant or dignified experience, so the Guild/Union was formed to mediate between the two parties.
Again, I didn't work out the details, but it does mean that there may be charges to enter some dungeons and levies/taxes to pay on leaving, as well as monster hirelings who prefer a business arrangement over being ripped out of space.
'Wilbur Whateleys'.
Of various sizes, shapes and levels of power, these are the abandoned children of the Great Old Ones.
Every one is unique. Some of them could be PCs. Most of them are not happy.
The Gods of Earth.
Break out a copy of Deities & Demigods or similar. Pick any or all of the gods (if you have a really old copy, leave out the Cthulhu Mythos ones), and grind their stats down almost to nothing. With random access to some of their old powers, and carrying some of their old baggage, set them down on the earth with amnesia and let them loose.
They're not going to recover from the thorough kicking Reality has taken, but they might end up with followers/worshippers again, and they're vulnerable to exploitation in a way they weren't when fully divine.
Port Sunlight.
The shining city on the coast (you decide). A beacon, a legend, a metaphor amongst the human and other mortal survivors of the planetary cataclysm.
Lady Malton exercises absolute power, and permissions to access even the outer wards of the city are notoriously hard to obtain and the qualifications are punitive.
No one has seen Lady Malton close up and unmasked, and no one knows for sure her rise to power. She is responsible for controlling the spread and availability of magic/spells (limited only to where she is able to exercise this).
It is said Port Sunlight sends out recruiters to populate the inner wards of the city.
Port Fishoil.
The greasy industrial counterpart to Port Sunlight, teeming with mortals, Deep Ones, Ghouls and few Shoggoths (who set up oversized inns and play the creepy, avuncular host).
Lord Cobain very strictly controls the fishing and trading fleet (composition and extent depends on how long since the apocalypse), and law-enforcement within Port Fishoil, and across the countryside right up to the outer walls of Port Sunlight. He is ever-present and ever-vigilant.
Cobain and Malton appear to be co-rulers, but the exact relationship is uncertain.
The Resurrectionists.
Members of this faction are normally only ever encountered after death. They resemble adventuring parties, but better armed and prepared than yours.
Focussing on 1st-3rd level characters, they find those who have died in dungeons and in the wilderness, and return them to life. This places you in an unspecified amount of debt, payable at some future date and in unknown form.
Only rumours are known regarding their motives, origin and headquarters.
The Sacerdotal Matriarchies.
Looks like a Puritan-era colony along the nearby coast, but cut off landward by densely wooded mountains and flooded valleys. For the last however-long-you-like, only women and girls have been seen for sure - the men and boys are apparently fighting a defensive war somewhere in the interior.
Outsiders are not welcome beyond the shoreline trading posts, so details of the Sacerdotal Matriarchies are scant, out-of-date and sometimes utterly unbelievable.
If you like, the Matriarchies are the best/only source of firearms, gunpowder and full plate armour; in any case, they are protected by heavily armoured, well-armed, mounted knights (women), who maintain a threatening, visible presence during trade.
Fear of Little Men.
I don't know when it was dropped, but Call of Cthulhu 2e has a pixie or sprite in the non-Mythos bestiary. The notes refer to them dropping in to 'loosely run' campaigns, and Stranger Aeons is that campaign.
There are pixies and there are sprites, and they have always been rivals. Since the apocalypse, they have seemingly entered an era of total war; increasing their numbers and expanding their range and committing atrocities.
For both sides, there is only the War and death, victory or defeat. Both sides are utterly contemptuous of other creatures, seeing them only as resources to be exploited, captured or denied their enemies.
Commentary.
As a contextual P.S., it was trying to make Stranger Aeons that put me back in touch with ttrpg.
Between family and work, I can't really justify the time to go so deep into my notebooks nowadays, so this has mainly been from memory; its light on detail and specifics, and I can't be sure of my references. It was mainly made with D&D in mind, my knowledge at the time being surest on BECMI and AD&D 1e and 2e.
Originally intended as a 16 page module/zine for an art exhibition when I still had an art practice, the tone is all over the place because it wasn't meant to be the thing it purported to be. There is also a deliberate element of 'pulled out of my ass/a hat'.
Part of my motivation was that there appears to be a greater willingness to work further from the source material [edit: in Mythos/Lovecraftian fiction], whereas there seems to be a tendency to cleave closer to a/the canon in core gaming materials - things can get more interesting in scenarios and supplements.
[Edit: Since writing, I've seen Trail of Cthulhu material - and that's sort of the greyer area coverage I'm thinking of]
The easiest way to start reimagining the Cthulhu Mythos was to chuck most of it out of the window, and then put back in the bits I like without worrying how they fit. It's now closer to the level of the mundane and the human; they're not really so alien to us (the consumer of media) anymore, even if they ever were.
