The law of Familiarity

Ever since the material and spiritual worlds merged, the geography of the world changed completely. Aside from a few protected locations, the world's appearance changes based on who perceives it and how well they remember the world before the Extinction. Familiarity is measured on a scale from 5 to 1. While high levels of Familiarity can exclude some of the more abstract changes to the world from appearing, even the most familiar places can still be affected by the Spirits or Lords that inhabit them.

Level 5

Level 5 of Familiarity describes a place known and remembered completely by the one visiting it. Those places retain their appearance and location from before the Extinction. The one unusual thing about them is that any changes done to them by one person won't be reflected in another version of the same place visited by another person, who is as equally familiar with it. For changes to "spread" from one version to another, the two people would have to meet in this location, and the changes may still not stick around after leaving the place once one of the visitors forgets about them. The only supernatural changes that show up on the 5th level of familiarity are the shortcuts and changes related to holidays that show up everywhere.

Level 4

Level 4 of Familiarity describes places that are mostly remembered by their visitors. Compared to the places assigned with level 5, these locations bear the marks of the destruction caused by the Extinction. So while someone might visit a place they knew in their past and recognize it, most of it could be in ruins or completely wiped out. Additionally, the few places in the location one never visited might be replaced by some weird things that shouldn't show up in such a place. Examples of said replacements are spatial anomalies, impossible geometry, pieces of different architecture, or geographic locations.

Level 3

Locations of the 3rd level of Familiarity show up in places only partially known by their visitors. This level usually shows up in the places one visited only a few times or visited so long ago, their memory of them is hazy. These places are an equal mix of what they remember about the place, what their minds construct in the blank spaces, and completely forgotten and now abstract distortions, creating a patchworked landscape. This level of Familiarity can lead someone to some interesting places. For example, visiting a mall could open up a world of weird shops where one could buy stuff human eyes have never seen before.

Level 2

Locations of the 2nd level of Familiarity show up in places one almost doesn't know at all. Maybe they had the location described or maybe they remember seeing a photo, painting, or a movie happening in said place. This is the last level at which man-made structures still show up, although even they tend to be distorted and warped. When venturing out of the safe places, but while still remaining inside the cities (or other areas known to travelers), it is really unlikely that the Familiarity will go lower than this level. That's because unless something affects the mind of the traveler, they probably should know that they are still near the locations that were more known to them (one wouldn't think they are in the middle of the forest when they just were in the middle of a city).

Level 1

Things of the 1st level of Familiarity are the places that while being different, sometimes try to mimic the material world, while doing so badly. Forests made out of objects known to people or things that try to resemble them, buildings with architecture born of demented dreams, geography resembling the art of Salvador Dali or M.C. Escher.

Level 0

Level 0 affects the locations one never visited and doesn't know anything about them. These places are weird and abstract, their geography and natural laws affecting them are alien and warped from the normal understanding of the world.

Traveling in groups

The more people travel together, the higher the chance one of them will know the place. Usually, locations reflect the level of Familiarity that is the highest in the group, so if someone in the group only heard about the place and the other person visited it before, the appearance of the world will reflect the memories of the one who visited the location before. However, the places that are unknown will now be affected by the minds of everyone who doesn't know the place, creating more abstract structures even in locations of a high level of Familiarity. Additionally, if two people's known areas intersect each other while being on the other levels of Familiarity, the border between them will usually become more abstract than it should be in said area.

Getting familiar with unfamiliar

When visiting some of the unknown but distinctive places, memories of them might etch themself into the mind of their visitor, forever affecting future visits to said locations. While this won't raise the level of the Familiarity of the location, some characteristics can show up again and again. For example, a low-level Familiarity place filled with gears visited later could appear as mechanical in some different way or show up with patterns resembling gears on the landscape.

Level -1

There are some rumors of places so little known by people who still remain after the Extinction that they become too abstract for human comprehension and too dangerous to survive. In those places, the humans themselves are treated like the ideas by the world around them. They can be shaped, changed, warped or even extinguished in mere seconds after visiting them.