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 Post subject: Random Starsystem Generator for space opera RPGs (for IPPro)
PostPosted: Wed Mar 16, 2011 2:05 pm 
I thought I'd share the star system/sector generator I've been working on for Inspiration Pad Pro.
Sector2 Random Generator

(Inspiration Pad Pro can be found at http://www.nbos.com/products/ipad/ipad.htm)

It's an amalgam of a number of SF system generators, cherry picked for the best bits and seasoned to my personal taste. It's definitely for Space Opera rather than Hard SF, but it does have a seed of real science that the GM can expand upon if they so wish. I'd estimate about 80% of the systems it generates will have an inhabitable world suitable for adventuring.

Although it's setup by default to produce a Stars Without Number sector, the table options allow you to change the number of systems or the size of the co-ordinate system it uses, so you could use it to generate individual systems if you like. Or alternatively 1000 worlds on a 100x100 grid takes about four seconds (good luck mapping that one!)

Sample Output

(4,6) Arte
GV Yellow star with 9 orbits.

* Asteroid Belt
* SuperTerrestrial Planet with 1 moons
-- Small Terrestrial
* Small Terrestrial Planet with 1 moons
Atmosphere - Breathable mix
Hydrosphere - 50% Water
Temperature - Frozen
Biosphere - Human-miscible biosphere
Population - Billions of inhabitants
TechLevel - 3-Medieval
Resources - high grade Metal ore, Value 5 and Precious Metal(s), Value 3
World Tags - Bureaucracy and Theocracy
-- Rocky Asteroid
* SuperTerrestrial Planet with 1 moons
-- Small Terrestrial
* Icy Dwarf Planet with 1 moons
-- Rocky Asteroid
* Rocky Dwarf Planet
* Terrestrial Planet with 2 moons
-- Rocky Asteroid
-- Rocky Dwarf
* Asteroid Belt
* Rocky Dwarf Planet
Sector2 works on the following assumptions.

1) The generator is designed for Space Opera rather than hard science. As a result the generator is biased towards producing systems with habitable worlds and interesting places suitable for adventuring. A realistic sector full of red dwarf stars with no habitable planets isn't going to make for a fun campaign. It also produces very little in the way of hard numbers, in order to give the GM more leeway. Like any random starsystem generator, it's largely up to the GM to interpret the raw results, at which point they can add "hard" science data back into their interpretation of the results if they wish. For example, if a red dwarf star did have a habitable planet, a "soft" SF GM can happily treat it as a standard garden world, whereas a "hard" SF GM can infer that it's tide-locked to the star, with all that entails. A GM looking at an impossible or unlikely system result (e.g. toxic, lifeless world with a population in the billions) can either veto the results or use them as inspiration for adventure seeds (why so many people on such a hostile world? Maybe they're slaves. Or maybe there was a "gold rush" on this world and now they're stranded)

2) The generator assumes a narrow habitable zone, large enough only for one planetary orbit. If a world in that orbit has terrestrial-type moons, they are also assumed to be habitable. The generator also assumes that any world that is even marginally habitable is inhabited. This is appropriate for an old setting, where space has been colonised for a long time, or possibly an ancient precursor race has artificially seeded worlds in the past. The GM should feel free to tweak the results dependent on the setting and their own requirements. For example, you may want more uninhabited garden worlds if the game is about colonizing a new frontier. Or you may want to eliminate populations on worlds where they wouldn't survive without significant artificial help. On the other hand, you may want to add colonies or bases on worlds outside the habitable zone, or even decide that a world in an orbit adjacent to the habitable zone was close enough to be a suitable candidate for Terraforming in the past.

3) Current astronomy suggests that our solar system is home to hundreds if not thousands of orbital objects of dwarf planet size or smaller. Planets of that type produced by the generator are assumed to be of some particular signficance (e.g. contains a particularly useful resource, or the site of a ruined ancient base). Assume there's a large number of other, unremarkable objects scattered around the system.

4) The generator assumes (incorrectly, it turns out) that planetary systems won't form in Trinary star systems, or other exotic cosmic objects (like pulsars).

Star Categories

Sector2 uses the standard stellar spectral & luminosity class system, of a letter and a roman numeral. (http://en.wikipedia.org/wiki/Star_categorization for more info) but also lists a plain-english description for GMs that don't want to get too bogged down in the science.

Planet categories

Rocky/Icy Asteroid - an irregularly shaped object with no atmosphere.
Rocky/Icy Dwarf - a mostly spherical shaped object, significantly smaller than our Moon. The assumption is that these are too small to hold any atmosphere and therefore aren't habitable, however an option exists to allow habitable rocky dwarfs for wilder settings (or
Small Terrestrial/Terrestrial/SuperTerrestrial - Earth type rocky planets. Small can be anything from Luna to around Earth sized, Terrestrial is roughly Earth sized, Super- is significantly larger than Earth. The exact sizes are deliberately kept fuzzy.
Hot Jovian - a jupiter type world in the inner star system, heated to very high temperatures by the star.
Jovian - a jupiter type gas giant world, found in the habitable zone and beyond.
Ice Giant world - a world like Neptune or Uranus made up of frozen material

Planet Qualities

Airless - no atmosphere, zero pressure
Trace - wispy trace atmosphere, still need a pressure suit to survive.
Thin, breather needed - tolerable pressure but low oxygen count
Breathable mix
Breathable but tainted - nature of the taint is up to GM, but should
Thick atmosphere, breather needed - too much atmosphere, requires breather to thin it out
Inert - the mix of gases isn't particularly poisonous, just not breathable.
Toxic - exposure to the atmosphere (even via the skin) is poisonous
Corrosive - the atmosphere attacks non-biologicals (like acid) as well as being poisonous.
Toxic & Corrosive atmospheres can be protected against, however there's a 50% chance of each being Invasive, which means they will gradually seep through any protective measures put in place.

Gives a percentage range of the planetary surface that is covered with liquid. The default is liquid water, however hydrocarbon and inorganic liquid seas are a possibility.

Gives a range of temperature options from Frozen (coldest day on the Antarctic) to Burning (mid-day in the middle of the Sahara). Assume that those two extremes are right out at the very edges of human tolerance and even a little beyond, requiring protective gear to survive. "Variable" represents a temperature that shifts over time and can be the result of either seasonal effects caused by axial tilt (in which case the temperature will also vary regionally) or through an elliptical orbit in which the planet moves closer and further away from the star (in which case the whole world is affected at once) (A GM running a more realistic game should assume the temperature generated is an average, and very temperature by latitude, e.g. a hot world might be completely uninhabitable at the equator, while the poles are a cool, temperate zone.

This shows whether the native non-sentient life forms (plants, animals) are compatible with human biochemistry. If not, you can assume that any population will have imported its own food sources raised artificially separated from the native biosphere. A Hybrid or Engineered biosphere is one where foreign life forms have been introduced to the biosphere to replace or coexist with native forms.

The generator assumes a predominantly human or cosmopolitan mix of population. Assume "Alien Civilisation" to be something outside the campaign norm. If you don't want to introduce non-human aliens to a humans-only setting, this could mean bio-engineered or divergent evolution variant humans, or maybe even normal humans but with a society vastly at odds with the campaign norm (such as a "hive" mentality)


This is the Tech Level scale I use, it should be easy to map to your preferred game system.

0-Stone Age (virtually no technology, hunter gatherer existence)
1-Bronze Age
2-Iron Age
4-Age of Sail & Gunpowder
5-Industrial Revolution (19th Century)
6-Mechanized Age (early 20th Century)
7-Nuclear Age (late 20th Century)
8-Digital Age (21st Century)
9-Interplanetary Age (colonisation of the star system)
10-Interstellar Age
11-Advanced Interstellar
12-Pre-singularity Age ("magic")

I work on the basis that the current campaign is generally at the cusp between the Interstellar and Advanced Interstellar ages, giving the difference between familiar, tried and tested technology (Interstellar) and state-of-the-art, better than current tech (Advanced) (NB - this isn't perfect yet. For the next version of the generator I'm thinking of folding in Iron Age and Medieval together and adding an "Early Interstellar", in which case the current campaign will always be squarely at the "Current Interstellar" level.)

Pre-singularity represents a level of technology where cosmic forces are casually manipulated. Instantaneous FTL teleportation, matter creation or anything sufficiently advanced to appear as "magic" from the perspective of the current campaign technology level.
Singularity/Ascension represents godlike abilities totally beyond human comprehension.

The generator gives habitable terrestrial-type worlds the chance of possessing some valuable natural resources, rated from 1 to 5, in these arbitrary categories.

Metal Ore, (low grade/high grade)
Minerals, (low grade/high grade)
Radioactive Ore
Raw crystals
Precious Metal(s)
Precious Gem(s)

Note that the "precious" resource types are assumed to not be for practical or industrial use, but purely based on rarity, shininess and perceived value. This will vary from campaign to campaign.
(note - the next version of the generator will generate these resources for non-habitable worlds as well)

World Tags are mostly taken from Stars Without Number, and are intended as a jump-start to GM creativity. See the world creation chapter for more details, or just google the phrases for inspiration.

[Note on Gravity. The generator currently doesn't assign a gravity property to the planet, leaving it to the GM. A world's surface gravity is determined by its mass, and in the case of Earth, 99% of its mass lies in the planetary core. So while a Small Terrestrial is likely to have lower gravity and a Superterrestrial likely to have higher gravity, it's be no means a concrete Thus a small terrestrial world with a larger core but thinner mantle and crust might have heavier gravity than Earth. This is something left to the GM to work out based on the other planetary properties. For example, a terrestrial world with no atmosphere might suggest a lower gravity unable to hold an atmosphere, while an otherwise perfect garden world with no or low population might be subject to crushing high gravity. In the next version of the generator, when I hope to include gravity as a generated property, I'm using the following scale.
Fractional - 0.1G (walking on the moon)
Low - 0.3-0.7G (walking on Mars, significantly lower than earth normal)
Slightly Low - 0.7-0.9G (you might feel a bit lighter, but it won't significantly affect your performance)
Normal - 0.9-1.2 (round about what you're used to)
Slightly High - 1.3-1.5G (you might feel a bit heavier, but it won't significantly affect your performance)
High - 1.6-2.something (you're significantly impaired by the heavier gravity
Crippling - ordinary humans are effectively immobilised by gravity, requiring supreme effort to even move
Crushing - gravity strong enough to physically damage the human body, snapping bones and causing organ failure.]

Stars Without Number (http://www.sinenomine-pub.com/)
Larry Moore's Star System Generator (http://www.starfrontiers.us/node/3518)
Starblazer Adventures (http://www.cubicle-7.com/starblazer.htm)
"Elite" by David Braben and Ian Bell (uses the name source string, but not the naming algorithm)
+ countless Wikipedia articles

Joined: Sat Dec 05, 2015 6:46 pm
Posts: 1
 Post subject: Re: Random Starsystem Generator for space opera RPGs (for IP
PostPosted: Sat Dec 05, 2015 6:50 pm 
I know this is an old post but I just had to say Thank You Very Much for this.

Thank You.

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