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GameMastery Guide / Creating a World / The Cosmos

Other Worlds

Source GameMastery Guide pg. 164
While solitary planets are common in our universe, why restrict yourself to one world? Try roughing in some other planets in your solar system—such worlds spawn strange beasts and give you entirely new campaign settings to explore. In creating these planets, remember that rocky worlds like Earth form close to the sun, and gas giants farther out. But that doesn’t mean you can’t have playable worlds all the way out to the system’s edge—captured bodies like asteroids and planet-sized moons around gas giants make wonderful solid worlds. A full solar system lets you play with planetary characteristics that are likely too extreme for your base world, such as the following.

Tidal Lock: A tidal lock is when a celestial body keeps the same side facing another body, such as Earth’s moon with its visible face and mysterious “dark side.” If a planet always kept its same face to the sun, one side might boil while the other froze. Would cultures live solely on the line between night and day? Would creatures and cultures evolve separately on the light and dark halves, and what would happen if they came into conflict?

Tidal Heating: For tidally heated worlds, the pull of another gravitational field (such as that of another planet) warps the planet’s shape, causing stress and friction to create massive outpourings of heat in the form of steam and lava.

Eccentric Orbit: Some planets have eccentric, elliptical orbits that make their seasons drastically uneven. If your planet slingshots quickly around the sun and then passes back out into the darkness for a thousand-year winter, what sort of creatures and societies would evolve?

Orbital Interactions: A planet that passes through a cloud of dust, comet tail, or asteroid belt at the same time every year might have anything from regular meteor showers to a rain of fire or even an extinction-level impact. Likewise, two planets passing close together in their respective orbits might offer a chance for interplanetary travel (both benign and destructive), communication, and so on.

Atmospheric Conditions: On Venus, the atmosphere is so thick that the wind is like a brick wall slowly scraping across the landscape. How would characters survive on a world whose very air crushes them, or whose air is thinner than on the highest mountaintop?

Transient Object: Perhaps a world is just passing through, an object pulled off-course by the sun but still bound for distant stars. What strange discoveries might it offer, and how would its residents treat the worlds it passes near, knowing they’ll never be back this way again?

Dying Sun: All things have their end—even the stars. Perhaps your sun is on its way out, and while your primary planet hasn’t been affected, its neighbors are suffering. This might mean a society falling into anarchy as reduced light cripples its agriculture, or a race for escape as the red-giant sun reaches out to consume nearby worlds.

Archives of Nethys

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Other Worlds