Random Planet Generators

I prefer to roll my planets the old-fashioned way: with dice and beautifully detailed tables (I’m looking at you, Stargate RPG). That said, we don’t always have the time to lovingly handcraft a new planet, which is where random generators come in handy. In addition to providing summaries of new worlds for immediate use in your campaign, they’re also a

Chaotic Shiny: Planet Generator: A dead simple generator capable of generating between 1 and 15 planets. Its summaries hit the high notes; gravity, length of a year, number of moons, types of landmasses, size compared to Earth, and an orbital summary.

This planet has 0.11x earth gravity, a 402-day long year and 15 moons. It is 54% land mass with 7 continents and is 2.5x the size of earth. It has a slightly ellipsoid orbit and 20-hour days.

SciFi Ideas: Planet Generator: Creates a simple, three-line planet with a name, a location, and a short description.

Planet Name: Banton 5
Location: Bantonine System
Description: A large gas giant with an atmosphere mostly composed of hydrogen. There are two giant storm systems in the planets atmosphere (similar to the Great Red Spot of Jupiter). The sentient inhabitants of one of the giant’s moons believe these to be the ‘eyes’ of the planet, which they worship as a god.

Planet Map Generator: If you want to work backward from a map of your world, check out this planetary map generator. Available in an online version as well as an offline windows version, Planet Map Generator will create a fractal map for you based on a random seed. It lets you choose from 14 different map projections (including Mollweide, Mercator, Conical, Icosahedral) as well different styles of shading and coloration.

An oval shaped map of a planet. Land masses are green, orange, and red, oceans are light to dark blue.
A world generated using the Planet Map Generator utilizing the Mollweide projection.

Donjon: SciFi World Generator: A fractal world generator lets you specify map projection and palette (e.g. the Earth-like “Atlas” and the red sands of “Martian”). You can have it randomly generate a name and percentage ice and water, or specify those values yourself. Hitting the “create” button gives you an atlas-style view of the planet including its type, radius, surface area, gravity, escape velocity, rotation period, axis tilt, atmospheric type, and more.

Property Details
Physics Type: Large iron/silicate
Radius: 9219.47 km (1.45 x earth)
Surface Area: 1.07 x 109 km2;
Land Area: 5.45 x 108 km2 (3.66 x earth)
Mass>1.72 x 1025 kg (2.89 x earth); Density5.25 g/cm3 (0.95 x earth); Composition: 44.2% iron, 37.6% oxygen, 15.4% silicon, 2.8% other metals, trace other elements
Gravimetry Gravity:13.48 m/s2 (1.38 x earth)
Escape Velocity15.77 km/s
Rotation Period: 21.65 hours
Axis Tilt: 24.25°
Hydrosphere Water: 50%
Ice 10%
Atmosphere Type: Dense reducingPressure154.15 kPa (1.52 x earth)
Composition79.3% carbon dioxide, 20.7% methane, trace other gases
Climate Type: Standard
Min Temp: 287 K (14 °C)
Avg Temp: 296 K (23 °C)
Max Temp: 301 K (28 °C)
Civilization Type: Scientific Research Station
Population: 1213
Tech Level Spacefaring (orbital spacecraft, cybernetics, laser weapons)
Special Features: Planetary rings
A world map. Land masses are light yellow and green; water is light blue and blue.
A world map created using the Donjon planet generator.

En World: N.E.W. Terrestrial Planet Generator (no longer available): Creates a planet using rules from the N.E.W. science fiction RPG. Less detailed than Donjon’s and perhaps a little more user-friendly for people who aren’t into the nitty-gritty details of the planet. Particularly nice is the human-readable summary of the planet.

Mu Centauri III, otherwise known as HiJak, is a medium-sized icy planet orbiting a red carbon star and is a super-rich bronze age homeworld.

Mu Centauri III Medium-sized Icy Planet Parent Star Type: C (red carbon star with 5 planets) Gravity: 0.9G Atmosphere: Thick Features: Rings Civilization:

  • Wealth: Super-rich
  • Technology: Bronze age
  • Type: Homeworld

Satellites: 2 moons

  • Gowron; small swamp moon
  • Divok; small terrestrial moon

Zarkonnen’s Planet Generator: A simple generator that has no user-specified settings. It spits out a simple summary of the planet (geographic features, notes on life forms) and some generic game statistics (industry, science, size, habitability). It also creates a cool linking rotating world, complete with cloud effects, but the inability to link to a particular planet makes it impossible to reference in-game

Orivim II

A sandy desert lit by a bright blue sun. Deep canyons cut into the planet’s crust. Clusters of grey fronds. Massive herds of three-legged, brown beasts move across the planet in time with the seasons. Their heads have three horns. There are many dormant volcanoes.

  • Habitability: 50%
  • Size: 5
  • Industry: 6
  • Science 3
A spherical world with white and pinkish clouds.
An example of one of the worlds created by Zarkonnen’s Planet Generator.

Jarett Gross’ Procedural Planet Generator: Looking for something more abstract? Check out Gross’s planet generator, which builds planetary illustrations based on several different shape types (triangles, hexagons, flat hexagons, pop-out hexagons) as well as a variety of planet and noise properties.

A spherical, hex-based world.

Experilous’ Planet Generator: Experilous offers another hex-style map, but this one lets you specify options like “tectonic plate count”, “oceanic rate”, “moisture level” and “Heat level”. Once generated you can quickly change between three map projections: glob, equal-area map, and Mercator map. The tool also gives you different displays to show types of terrain, tectonic plates, elevation, temps, and moisture.

A hex-based world. Green and brown hexes are land; blue hexes are water.

Hypertext d20 Fantasy World Generator: This generator will build a full-fledged fantasy world map — complete with named cities, seas, rivers, and ruins — from a few starting parameters, namely the percentage of water and ice featured on the world. You can turn of extras like the city, hex, and label generation, but either way its great fodder for your next global hexcrawl.

A rectangular map of a fantasy world. The land and oceans are divided up into hexes, some of which are labeled with location information.
An example map created using the Hypertext d20 Planet Generator.

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A fractal map created by the Planet Map Generator.


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