The Observer Problem (en Inglés) - Nox Vale

The Observer Problem is a philosophical horror tabletop RPG about collapsing realities through the simple act of looking.

There is no hidden truth waiting to be discovered. The world begins unfinished - genuinely incomplete - and every observation, every question, every commitment forces it to become something more specific... at a terrible cost to the observer.

In this game you do not investigate a mystery.

You are the pressure that finishes the mystery.

Players take on the role of Observers whose Tendencies (Precision, Assertion, Doubt, Pattern-Seeking) shape how they interact with an ever-shifting probability map. Every time you collapse a Held state into a Fixed fact, you spend your own Stability, raise Entropy, and risk Noisy additions, Fractures, or outright Rejection by reality itself.

The more you define the world, the less room it has for anything else - including you.

The Observer Problem includes the complete core rules plus the five-session campaign module:

The Cartographer's Unfinished Country

A decaying territory mapped by a cartographer who understood the danger of finishing his work. His incomplete maps are already load-bearing. Your presence will break them.