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Archives of Nethys

Archives of Nethys

Pathfinder RPG (1st Edition) Pathfinder RPG (2nd Edition) Starfinder RPG

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GM Core / Chapter 2: Building Games / Building Worlds

Cosmology

Source GM Core pg. 140 2.0
An enduring curiosity among many cultures is to ask what wonders lie beyond the night sky. Does anyone gaze back from the moon above? What realms do the gods call home, and what is it like to walk in their divine presence? Is the mortal world at the center of the universe, or is all life utterly insignificant? Spiritual ponderings like these are central to belief systems across the globe. As a world builder, you get to answer those enduring questions by designing the multiverse in all its inexplicable grandeur. The following are some aspects of your cosmology you might consider, but as you decide these, you should also consider how many of these details are known in your world—and by whom.

The Universe

Source GM Core pg. 140 2.0
The reality in which mortals live out their short existence is known to sages and scholars by many names—the Universe or the mortal realm, among others. The structure of the physical universe might follow any of the following models, or it might be something completely different.

Vast: The universe is an unimaginably sparse void of infinite space, littered with stars, planets, and various bits of detritus.

Limited: The physical universe in your campaign world may be smaller in scope yet far more fanciful. For example, in Hinduism, the cosmos is supported on the backs of four elephants, themselves standing upon the shell of a world-sized tortoise, whereas Norse cosmology describes nine worlds connected by an immense ash tree.

Bizarre: Sometimes the universe is more complex than the previous two categories, or possibly nested within multiple realities. What if the universe the PCs first know is in fact a magical or mechanical simulation of such complexity that its inhabitants are unaware that they themselves exist as an artificial consciousness?

Composition of Outer Space

Source GM Core pg. 141 2.0
The spaces between the stars can also affect the stories told in that world.

Vacuum: In conventional astronomy, outer space is an immense void existing in a near-perfect vacuum. In some settings—including the Age of Lost Omens, where it is known as the Dark Tapestry—the trackless firmament between the stars is an ominous expanse home only to terrible beings of incomprehensible malice.

Endless Sky: What if the blue sky overhead extended outward forever? One need only fly high enough and far enough to reach another world.

Celestial Spheres: The ancient Greeks posited that planets, stars, and more were embedded like jewels within celestial orbs of quintessence nested within one another.

Solar System

Source GM Core pg. 141 2.0
What is the shape and structure of the solar system containing your game world?

Heliocentric: Physics dictate that all planets in a system orbit the sun.

Geocentric: What if your game world is in fact the center of the star system, or perhaps even the center of the known universe?

Dyson Sphere: Perhaps a solar system has been enclosed in an artificial structure designed to harness the power of the sun.

Planets and Moons

Source GM Core pg. 141 2.0
In antiquity, astronomers noticed that some of the twinkling lights in the night sky moved differently than the others. In time, these celestial wanderers would come to be known as planets, many with their own complement of orbiting moons. Are there other planets orbiting your world’s sun? Are they terrestrial, gas giants, or something less common? How many moons are there? The characters may never venture there, but celestial bodies can have a strong influence on a culture and help you describe your world in an evocative and distinctive way. In some campaigns, you might even want to set adventures on these celestial bodies.

The Multiverse

Source GM Core pg. 141 2.0
In Pathfinder, the physical universe of your world is one plane within a much broader multiverse. The Planes, on page 172, details how planes work and the multiverse of the Age of Lost Omens, but you can fit planes to your story and world, or even build a new multiverse from scratch! Perhaps there are only two planes beyond the material Universe, diametrically opposed and fighting over mortal souls, or the multiverse consists only of a series of infinite alternate realities. The options are truly endless, limited only by your imagination and the story you want to tell.