Backrooms

A possibly sentient pocket space that replicate the architecture that comes in contact with, usually making small rooms and corridors that seem endless. It randomly intersect with our dimension, creating invisible entry-points that don't last very long, and without specialized tools it's impossible to escape.

The replication

Backrooms in it's blank state

The replication recreates everything from near the entry point, walls, floor, ceiling, even objects but only lifeless objects. Scans show that copies are identical at atomic level and distance from the entry point doesn't seem to affect the object at all. After years of study it was found a way to create lasting entry points called doorways.

Some believe that this is a defense mechanism but that would implied that the whole dimension could be alive or at least controlled by something at some point.

The current working theory of how this works is that starts replication our copying everything near the entry point the moment it intersects with our dimension, all though it can be confirmed for sure because the intersection never leads to the same place. And it doesn't seem to obey the law of mass conservation but if it does its hard to observe or measure.

It also has "blank state" which is visible once you wander far from the entry point, the walls are covered in a yellow tinted wallpaper and you can find a power socket in every other wall, the floor has a brownish carpet that always seems to be slight damp and smell like they been in this state for quite a while, the ceiling is several fluorescent lamps spread at a somewhat uniform distance making well lit, everything seems to be old, around 30 years.

Potential Uses

Some corporation might be able to create a stable doorway and use the replicating mechanic to mass produce inorganic objects that are expensive.

Ingame Mechanics

Try to detect if the player has clipped through some wall or fell through the geometry and teleport them to the backrooms, and give them a soft game over screen, in which they can explore but make them aware then can't get out of there.