Time's Frayed Clue
Unrelated to any other settings or systems mentioned in this blog, this is a reposting of something I wrote back on the Delta Green list. At the time there was a scenario competition on the Delta Green list. One of the entries "Double Dog Dare" had to do with an uncontrolled skipping over to parallel timelines.
At around the same time there was some discussion of the problems associated with players having read the book enough that they could guess what mythos beasties they were up against in advance. Someone suggested, as a possible remedy, partially or entirely changing the names or descriptions of the various entities to throw off well read players.
These two ideas sort of coagulated together in my mind to produce the following:
Appropriating, swapping, and re-inventing the names and qualities of antagonists in games and literature is a fine old tradition. But mulling over the Agent Nancy discussion along with Jeff's "Double Dog Dare" scenario from the contest (also possibly having seen Primer recently) has given me the idea for a "meta" level to this identity shuffling. The idea is this:
1) Assume that the characters know a reasonable amount about the monsters in the game and tell the players that on a mythos success they can even look up mythos flavor text in the rule book if they want.
2) They get access to some mythos text or other artifact that reveals to them a particular aspect of the True nature of reality. Preferably all the PCs should come in contact with the artifact within a short time of each other unless the keeper has some clever means in mind to deal with their inconsistent experiences (see later on). The artifact was created by the Elder Things, Mi-go, Shaggai, or some other group with independent race with developed aesthetic tastes and a frequent interest in Azathoth, Daoloth, Yog-Sothoth, or some similarly nebulous outer god.
Possibly the artifact that enlightens them and any text explaining the nature of the artifact might be totally separate requiring the characters to piece together their own understanding of the situation. One explanatory mythos text is "Time's Frayed Clue", a codex on causality and alternate worlds composed in a sort of "travelers guide" style.
Time's Frayed Clue has a few odds and ends about temporal and inter-dimensional traveling mythos entities and maybe a relevant spell or two. But the text's real whammy is an Insanely well crafted analogy comparing time to a string made from multiple strands.
"Multiple worlds" style quantum theories might suggest that for each possible quantum fluctuation in the universe additional universes come into existence so that for each moment there are a nearly infinite number of outcomes that could arise from it. But TFC goes a step further, implying that for each moment there are a nearly infinite number of different permutations that could have led up to it. It further goes on to suggest that the chain events which any given creature remembers leading up to the present moment are only one possible history out of many that could explain the universe's current state at that instant. All the other possible histories which a given sentient mind doesn't remember which lead up to this moment have equal validity.
It also states (perhaps incorrectly) that an understanding and mastery of this information is what gives a few entities like the great old ones and elder gods their power since these beings are aware of several or all of the possible ways they existed in the past as well as different versions of the present. There may be some indication that Hauster/KIY is particularly adept at this sort of thing. This whole text is treated in a way that seems to human interpretation almost light-hearted and witty, like the author wants you to think this is why Nyarlathotep always has that amused smile.
3) The character's world view is never quite the same again after accessing the artifact. Essentially their entire life now can be viewed as a memory recalled at the moment of death (or the death of the last character alive in the cell). The artifact opens the reader's mind to a small handful of the histories that never were. Essentially their memory may follow other chains of causality than the minds of most people.
This may have some bearing on the character's day to day life and human interactions, but likely very little. The character is human and human interactions are so trivial in the scheme of the universe that they have little power to shift the character's memory from a "probable" history of Earthly affairs.
For example a history of last week when the roads were paved with green asphalt and Incan god-kings ruled large chunks of South America may be equally as valid as the history in which the roads were blackish gray and the Incan empire long gone. But when the character died the history of black roads and an extinct empire seemed much more probable to their memory so that's what they recalled. Hence the "normal" earth is still the setting for an adventure.
On the other hand mythos entities, especially the bigger movers and shakers, have a little more pull in the world and on the characters newly empowered perceptions. This paradoxically means that you remember the dramatic different variations that might have produced your encounter with any given mythos entity more than you notice the different timelines of humanity. For instance Shudde M'Ell may seem it's normal tentacled self the first time encountered, but appear as some sort of insectile marmot-thing to other agents during the same encounter, or display unusual powers at a later encounter (like a twisting, slithering form of flight).
The differences between perceptions of a given entity within or between encounters may be directly affected by the sanity loss the entity induces. Normally the more sanity lost the greater the agent's recollection of the encounter will differ from that of other agents and from previous encounters with that entity. This could be a useful way to handle insanity in most cases as some characters start simply reacting to a situation as they see it, but not as other characters present see it.
These different perceptions of various agents could be a problem if teamwork is required to defeat even one manifestation of such an entity. But the differing perceptions could also be useful if the entity's nature requires that several different manifestations be attacked simultaneously in different ways for it to be defeated.
If variation of perception within an encounter is a bit much and you just want to stick with variation between encounters there's always this handy spell:
The Tie That Binds
The recipients of this spell will all be affected by causality in the same way for any given event they take part in. This generally means that their memories of mythos entity encounters will all be the same, although memory differences for reasons unrelated to branching causality may still occur (i.e. illusions and mind effecting spells or powers still work normally). Their memories of an entity or phenomena may differ between one encounter and the next, but will all differ in the same way (i.e. all agents remember the ghoul having black fur and hooves, but all now see that it has gray fur and paws). If The Tie is active on any given group of people during a supernatural encounter then sanity loss generally just indicates fear or other mental instabilities rather than different perception of the event.
The ritual requires all participants to chant for approximately 2 hours in a situation where every participant can hear the chanting of each other individual in the group. If any participant drops out of the chanting or can not hear the others for any reason the spell does not apply to that individual and they might remember/perceive later mythos encounters differently than their cell mates.
The perception synchronizing effects of this spell last for 12 days and may be renewed at or before that time. The spell costs 2 magic points and 1 point of sanity since the effects of the spell are largely intangible and not even perceptible unless mythos activity is encountered. For all agents who spend 1 POW as well the effects of the spell are permanent as far as memories and perceptions shared between them go. Agents may feel slightly paranoid afterward though, like there's something they should noticing be some dangerous situation they're on the look out for but keep missing.