When the Demiurge created the world with the four basic elements that it extracted from the Apeiron, it gave it a perfect tetrahedral shape.
Now, an eternity later, the world still keeps its shape, although somewhat erosioned since it disappeared.
Distinct living forms succeeded in each facet of the world, each more adapted to their environments.
- Noah is the facet of the earth moon. It is cold and dry. Fire lies far beneath the earth, and only in some points rises forming volcanoes. There is air above the earth, and water is restricted to seas and some rivers. Noah is the facet more similar to our world, but with a cold climate all along.
- Ignis is the facet of the fire moon. It is hot and dry. Here, fire has mixed with air. Only under earth can heat be withstood. There some few underground lakes, usually at great depths. Almost all great civilizations of this facet appeared in the colder underground tunnels and caves. The big exception was the great Trelo empire, which conquered all the facet and even reached out to Noah, and conquered it too.
- Bris is the facet of the air moon. It is hot and wet. Floating earth islands and changing seas fly in an enormous air ocean and, in its depths, a fire abyss roars. The cultures natives to Bris have typically been very isolated, as the floating islands are impossible to leave except to some very specifically adapted creatures. Also, “gravity” in Bris is different. Things do not always fall in a direction perpendicular to the facet plane: if there is near enough a floating island or sea, things fall towards it. Bris inhabitants who have visited other facets found them strange; inhabitants of other facets who have visited Bris found it, at least, disconcerting.
- Aquo is the facet of the water moon. It is cold and wet. A big ocean, with a few isolated islands. Rains and storms are common. And there is the Hollow. More or less in what would be the geometrical center of the facet, ocean dissappears, as if kept aside by an invisible spheric barrier. In the lower side of the sphere (up to, more or less, a quarter of its height) something has happened to water: it has transitioned towards a crystalline state distinct to ice. Under that crystal, the ocean can be seen. And above the crystal, somewhat unexpectedly, some great cultures have developed, always under the vision of huge ocean walls around them but never falling.