"Truths of the world… and a secret" is a worldbuilding tool

This tool is useful for kickstarting a new world for a story, or to introduce a existing world to other people (for instance, to players of a new tabletop role playing campaign).

It consists in enumerating up to six facts about the universe we are creating. These facts are usually known by the people who inhabit that world, and should be characteristic enough that separate this universe from other ones. For instance, a truth for Star Wars could be "The Empire governs the galaxy with an iron hand". For X-Men we could have "There are mutant humans who have superpowers".

My own twist is to remove one fact and add a secret to this list. For Star Wars, the secret could be "The Jedi are not extinct". I find the secret to be handy to create conflict and to spice up the world and/or some of the important characters.

As a full-fledged example, these are my five truths and the secret for a short novel I'm writing:

Five truths:

1. The main source of energy is orialite, a precious mineral who has to be activated by an arcane.
2. Arcanes perform magic by transforming matter into energy and viceversa. Dark matter can be used for this, too.
3. The Arcology is a colossal tower with political privileges. It's its own city-state.
4. The nobility holds the power, but a rising bourgeoisie claims more political influence.
5. The Arcology houses the most prestigious university in the world.

A secret:

• There's a technocratic secret society plotting to get to power, regardless of the cost.

I saw this for the first time at Nicole van der Hoeven's D&D campaign page, and the original source seems to be The Lazy Dungeon Master's Campaign Guide by Sly Flourish.