Solar System Generator

A while ago, I was hoping to start a game of “Stars Without Numbers”. It never happened, unfortunately, but it got me thinking about it’s world generation system. I like it, it’s neat, and it gives you a lot of ideas to play with. My big problem is that it doesn’t generate the entire system. So I went looking for others.

First stop, obviously, was Traveller. That’s pretty much the same, only the world isn’t quite as interesting, and the system that’s generated is basically nothing, just “Gas Giant: Y/N”. After that, I decided to trawl the Interweb for other things.

My problem with all of the ones I found is this: usually they are far too detailed, some especially so. “Alternity Cosmos”, a free PDF that is a custom patch for this problem in the game Alternity (pretty system-neutral, actually), is absolutely insane in the amount of detail. This is cool, but no-one would ever use all of the info, and therefore the tables will rarely get used (plus it takes like an hour plus to generate a full system). Others, while nowhere near as bad, have a similar problem: there is a lot of detail, and for each planet, you have to roll out all of that detail before you know what the planet is like. There’s all sorts of information: temperature, radiation, atmospheric pressure, atmospheric composition, gravity, orbital eccentricity, perihelion… All I want to know is: can the PCs go down there without a suit or not?

So, I have devised a short series of tables to rectify this problem. Here you go:
Planets potentially capable of supporting life have 2 stats: Atmosphere (A) and Temperature (T). Everything else is house-ruled. (1d3* = 1-3: 1, 4-5: 2, 6: 3)

Inner Zone: 1d6 objects, -1A
Habitable Zone: 1d3* objects
Outer Zone: 2d6 objects, -1A

Object: (Inner Zone -2)
1. Asteroid (Belt): 1d6 major asteroids; no A/T
2. Dwarf Planet: 1-in-6 chance of a moon; no A/T
3. Planetoid: 1d3*-1 moons, -1A
4. Planet: 1d3 moons
5. Small Gas Giant: 1d6 moons, -1A (Bespa-style)
6. Large Gas Giant: 1d6+3 moons; no A/T

Small Gas Giants have a 2-in-6 chance for a planet-sized moon (+1 T)
Large Gas Giants have a 3-in-6 chance for a planet-sized moon (+1 T)
All other moons are dwarf planets or smaller.
Planets with at least 2 moons get +1T

Atmosphere (roll randomly; -1 in Inner/Outer Zones)
1. Crushing/None/Corrosive, need suit (short-term only)
2-3. Dense/Vaporous/Toxic, need suit
4-5.Thin/Thick/Slightly toxic, need breathing mask
6. Earth-like

Temperature (6 in Habitable Zone, -1 per step in/out)
1. Boiling steel/absolute zero, need suit (short-term only)
2-3. Dangerous (Lava, liquid nitrogen), need suit
4-5. Uncomfortable, may require appropriate clothing (desert/arctic)
6. Earth-like

So, basically, if a planet has 6/6, it’s like Earth. If there’s a 4 or 5, people need protection to go down there, but it’s not especially hazardous. If there’s a 2 or 3, people need a suit. If there’s a 1, people need a suit to survive for minutes/days/hours/whatever.

If it’s going to be relevant, here’s another table:

1. Low Gravity (if atmosphere is not 6, it’s thin)
2-5. Normal Gravity (if atmosphere is not 6, it’s toxic)
6. High Gravity (if atmosphere is not 6, it’s dense)


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