Basic Information
This page generates random Planetary Systems and Star Systems, to aid with the creation of destinations in your Sci-Fi RPG.
Step 1: Star System
First you'll need to determine how many stars are in your system. In the majority of the cases, it's going to be one or two. Just over 50% of the stars that have been cataloged by science are binary star systems. Other data suggests that perhaps as many as 66% of the stars in the galaxy are solitary stars (most of them singular Red Dwarf stars). Regardless of which data you follow, trinary and other larger multiple star systems appear to be relatively rare.
- One option would be rolling a d6, and caring mostly about whether it's odds or evens - on an odd result it's a single star, on an even result it's a binary system. On a "6" you instead roll again and the system has a number of stars equal to the number on the second roll.
- Alternately, you could click on each of the three tabs below and decide which grouping sounds like the most fun.
- As a last alternative, it may be easiest to always go with single stars unless given a reason to do otherwise. Many binary or multiple star systems are spread out enough that planets each orbit just one individual star, anyway. Note however that the single star tab feeds from a slightly different pool of stars than the other categories, so you might want to mix it up a bit from time to time.
If you desire, larger systems (like the Sextuple system of Castor (Star)) may be generated by using multiple tabs together, or by waiting a few moments and then hitting refresh.
The "solitary star" tab always generates a star that can support life and the formation of planets. The binary and trinary systems include some more exotic star types, so there's some possibility of non-habitable systems coming up, such as a binary system where the only star entries were two types of black hole.
Step 2: Planetary System
This section generates planets, or at least broad categories of planet. You will need to determine how many planets you're using. Most systems will only have a handful of planets that are actually worth the trouble of colonizing, however. Assuming your main PC race is humans, there's not much point in settling in a system that has nothing but flaming balls of rock. So, we'll assume there's at least one planet worth setting foot on.
Step 2a: Habitable Planets
Habitable planets may still require some level of Terraforming, or even the daily use of advanced technology to survive on the surface, but they at least don't melt or freeze your ship within a few hours of landing, and they have something to land on.
You might roll d4-1 to determine how many habitable planets are in the system, with a minimum value of 1.
Step 2b: Stick A Hat On It
There's a long-standing Sci-Fi tradition of summing up planets by just one or two details. Often this is phrased as "It's like earth, but…" or "Like earth, but with more…" Other times, planets are presented as being a single environment, or the people of the planet all have one cultural or personality trait in common. See Planet of Hats for more ideas. On some level it's a little silly, but if your game is going to hop from planet to planet from session to session, it's probably a useful abstraction to just boil every world down to one or two concepts. So, a couple of random links are provided here to help you pigeon-hole planets…
- Nothing
- Politics
- Guild or Elites
- Cultural Template
- Single Biome Planet
- Aliens
- Megastructure
- Completely Random Concept
Pick a tab from the right to summarize the planet
For a more nuanced and realistic depiction of a planet's cultures, you could use our Random Nation Generator. Sticking a hat on it is meant just to give you a quick concept or two to improvise around.
Step 3: Other Celestial Bodies
Step 3a: Uninhabitable Planets
These are planets that a quick scan suggests would be too difficult for humans to colonize. Starfish Aliens or Sufficiently Advanced Aliens might not have a problem with it. If there's some resource rare enough, or populations are exploding back home, people might figure out how to make do, but in general you're better off putting your energies elsewhere. As a rule of thumb, assume every system has 2d4 such uninhabitable planets.
Step 3b: Other Bodies and Hazards
This section includes planetoids, asteroids, anomalous readings, and other navigational hazards that might suggest encounters in your setting.
Step 4: Adding your own ideas to your creation.
Customize those results, and work out whatever details you'll need.
Step 5 (Optional): Adding your own ideas to our creation.
If you come up with some awesome navigational hazard, alien or society concept, planet type, etc, you can add it to the feeds that supply this random generator. Add pages to the Arcana Wiki, and then apply the following tags to make the pages show up here:
- rps_starsingle - Used in Step 1 for categories of stars that can fuel a planetary system on their own. Not used for specific stars, such as Alpha Centauri or The Sun, but for categories like Solar Analog or Yellow Dwarf. Not used for black holes, brown dwarfs, or other bodies that wouldn't provide usable light and heat to their planets.
- rps_starmultiple - Used in Step 1 for categories of stars that might exist as part of a binary or multiple star system. Again, it's not used for specific named or numbered stars. However, it is, unlike rps_starsingle, used on stars that might not provide enough light for a star system on their own. It's also used for entries of types of multiples, such as eclipsing variables.
- rps_habitable - Used in Step 2a for planets that are relatively easy for humans to survive on. Planets that are really hard to colonize should get the rps_badplanet tag.
- rng_politics - Used in Step 2b for political issues and movements that might divide the planet. (Also used in the Random Nations Generator)
- rng_org - Used in Step 2b for organizations, businesses, social groups, etc. (Also used in the Random Nations Generator)
- rng_culture - Used in Step 2b for nations, civilizations, cultures, that the planet might be based on. (Also used in the Random Nations Generator) See also Planet of Hats.
- rng_terrain - Used in Step 2b for terrain features that are common to the planet. (Also used in the Random Nations Generator) See also Single Biome Planet.
- rps_alienlife - Used in Step 2b for aliens and exotic life forms, should that be appropriate to your setting.
- rps_mega - Used in Step 2b for orbital and stellar megastructures.
- rps_badplanet - Used in Step 3a for exotic or dangerous planets that would really hard for humans to colonize, like a Hot Jupiter.
- rps_hazard - Used in Step 3b for weird hazards, small planetoids, and the like. Includes celestial bodies too small to have an atmosphere, strange anomalies and dangers, external threats, etc. May also include nearby stars and objects that are not part of this system, but would have an impact on it just by virtue of being in the same portion of the galaxy.
