Just a convenient spot to put any pdf sector maps generated with the Travellermap.com tools.


Spinward Sector Trade Map

Spinward OTU data overlaid with my trade route adjustments


color code:

  • purple: primary routes (prime system to prime system)
  • dark green: secondary routes
  • light green: Imperium subsidized routes mainly to build up the frontier
  • others: non-Imperium

nb. green routes that connect to purple routes are both green and purple so have dual trade nature, part big ship universe and part small ship universe


note to self: need to redo trade route colors as there should be three cases:

  • hinterland routes (primary system to the systems in their hinterland)
  • primary route only (route joining two primary systems not part of a hinterland)
  • combined (hinterland route which is also a primary route)

the reason being that each route type would have a different mixture of ships so you know the “scenery” of a system wherever the players decide to go (and ultimately to provide the foundation for a mixed big ship vs small ship universe with the purple routes being big ship and the green routes small shop)


ATU Early Colonization Map

alternative traveller universe early colonization map using Vland sub-sector’s base data for convenience


color code:

  • all green as all early colonization and only one prime planet
  • amber system: unusual passive exotic threat of some kind
  • red system: unusual active exotic threat either being actively quarantined or actively fought in some way e.g. naval quarantine or active navy/marine bug hunt

starport code:

  • A: home world
  • B (with navy base symbol) established colonies (oldest/largest with self government)
  • B (with scout base symbol) newer colonies (colonial service)
  • C: fuel stops along routes to colonies
  • D: remote colonies, mostly research stations
  • E: minimal scout or colonial service refueling stations for remote colonies (possibly automated)
  • X: nothing

naval base in this context is a small compound with some admin, maintenance and refueling facilities and up to a platoon of marines maybe, 100 or so personnel, plus an orbiting colonial cruiser (c. 1200 dtons, crew 30+). full maintenance and spare parts only on home world.

colonies with a navy base will also have some kind of scout and/or colonial service facility but slightly separate


on reflection an early colonization map might be better with home world in the center of a home sub-sector with an inner ring of subsectors and an outer ring like:


O I I I  O




and then take one linear slice as the campaign setting so H I O with

  • the Homeworld sub-sector containing the home world and established colonies (more corporate intrigue)
  • the Inner sub-sector being more frontier with newer colonies (Firefly)
  • the Outer sub-sector still being explored (more Star Trek)




Minor Addendum

thinking aloud – a minor addendum for myself



still riffing on my current answer to this question which is: a good scifi RPG is one that helps you create the kind of scifi you want to recreate

for me, most of the time that means small ship, frontier scifi

so decide the setting you want first and then see which rpg best suits the setting


“Frontier space” Requirements

as much variety of story possibilities as possible within a reasonably compact area of space that the party can reach – not just repetitive exploration of alien worlds most of which wouldn’t have any life

beyond that compact area should be unexplored space to enhance the frontier mystery feel – which means you need a reason a scout ship can’t have explored 100s light years in every direction



my solution to those requirements is to have ship maintenance requirements that favor small ships and only a gradually increasing range as maintenance infrastructure is built allowing ships to explore further leading to a geography of an inner ring of 2×2 Traveller sub-sectors with the home world in the center, a middle 4×4 ring and an outer 6×6 ring where the home world has been colonizing long enough for
– the home system to be widely colonized with lots of shipping of all kinds
– the inner ring to contain a number of medium sized colonies (populations in the 100,000s) with a moderate amount of small ship trade and passenger traffic
– the middle ring to contain newer colonies still being developed with limited amounts of trade traffic and moderate amounts of colonial service traffic
– outer ring mostly only scout service

this allows for
– political intrigue, crime, trade type stories on the home world and in the inner ring
– colony creation and survival stories in the middle ring
– planetary exploration and survey in the outer ring
– research colony stories anywhere
– alien fauna and flora stories anywhere

  • some Cthulhu thrown in here and there

one downside to this type of setting where a home world is starting out on the process of colonization is it’s relatively low tech. one way to fix that is to add a lost alien civilization so any tech you want in the game from any of the Traveller books (or elsewhere) can be added in that way. high tech scifi tropes like Dyson spheres can also be added this way so your home world doesn’t have to be a super high tech society – which i personally find hard to imagine – but you can still have the players find things like dyson spheres on their travels.

  • Alien ruins including super high tech elements

so far so good



the only problem i had with this setting till now is the amount of backstory i’d potentially want for the home world: races, geography, history, evolution etc and how space exploration would be complicated if there were multiple large nations.

one option is to use earth, another is to make a ton of stuff up but a simpler 3rd option is to make the home world an ex-colony itself.

New Solution

so i’m going to posit a previous home world that started colonies in the same way as the new one is doing and along the way they found an alien artifact which they took home and it blew their solar system up (or something like that) leaving their small colonies to fend for themselves and the new home world is one of those ex colonies at the far edge of the previous civ’s exploration.

then say although the new home world had all the knowledge of the original they only had a small population at the time (say 200,000 or so) and thus needed 3-4 centuries to build up their numbers and productive capacity to the point where they can build starships again.

so the new home world might be a whole planet but the core is maybe an area the size of France around the original starport with a similar sized population (50-60 million) – which i think works well as the backdrop for a small ship Traveller universe.

it also adds another category of story on the planets back in the direction of the original home world: abandoned research stations, extinct colonies, surviving colonies, surviving primitive colonies etc. also if the new home world is say around TL10 while the original civ was say TL12 in some areas those old colonies may have some high tech loot.

just a small change but it works for me


Sciency Space

How many earth-like planets?


How Many Stars?


According to Wiki, near Sol it’s one per 0.004 cubic light years or 0.14 cubic parsecs (and this may not include lots of brown dwarfs). So that’s four stars in a 3D ten light year cube. In Traveller terms that would be a 3x3x3 parsec cube.

Assuming you want a 2D star map for convenience then you can hand wave the 2D map as a navigation projection, the space equivalent of a Mercator projection. I think this is a plausible sciency hand wave if your setting includes any kind of FTL subspace, jumpspace, hyperspace etc as it’s easy to imagine things like that involving strange geometry.

Either way this gives you four stars in a

  • 10x10x10 light year cube
  • 10×10 light year square
  • 3x3x3 parsec cube
  • 3×3 parsec square

or the equivalent in other sizes.

(The main point of the 2D hand wave is that four stars in a 3×3 parsec square is roughly 50% which fits the Traveller ratio making conversion easier.)


Types of Star

The current best guess is planets have to be in a star’s goldilocks zone – not too hot, not too cold – to start on the path to an earth-like planet. The goldilocks zone being where liquid water can exist.

(There are lots of possible exception to this like gas giant moons at just the right distance from the gas giant but goldilocks planets is maybe the default case.)

The goldilocks zone of a star varies depending on its type and at what stage it is in its cycle.

Two Categories

There are two base categories – stars that start out too big and those that don’t. The ones that start out giant apparently blow up too soon for planets to develop so they’re a bust (except as exotics).

The ones that don’t start off too big become main sequence stars. These burn a long time (billions of years) but change over time. As they gradually burn out to become red giants their goldilocks zone moves further out so a planet that might have been in the right zone for a few billion years can eventually find itself too hot or too cold.

Eventually main sequence stars flare up into red giants which would swallow up any previously habitable planets and then collapse into red dwarfs. Red Giants might have a habitable zone very far out from the star but although Red Dwarfs have a (very close) habitable zone I’d imagine any planets close enough would have been wrecked by the Red Giant phase (maybe exotic exceptions as always).

So for main sequence stars and maybe red giants, at any particular time there is likely to be a zone that has been in the habitable range for billions of years – long enough for the process of becoming earth-like to start if other conditions are correct.

(nb something that confused me for a while, if the time it takes to start the process is c. 3 billion years then older stars don’t necessarily have a greater chance because of the way the habitable zone moves over time. A star might have a lot of suitable planets in a neat row of orbits but depending on how fast the star it might not have enough time at each location to finish the process.)


Binaries, Trinaries

Also a lot of systems have multiple stars. Roughly

  • 50% single star
  • 39% binary
  • 8% triple
  • 3% four

Binaries can be in close or far orbit with those in close orbit thought to make it harder for planets to form. If we assume

  • binaries have a 50/50 chance of being close or far
  • triples are a close pair and one far
  • four are two close pairs
  • close pairs complicate the goldilocks zone
  • far single pairs with their own planets creates a double chance
  • assume close pairs have 0.5 chance and distant singles have 1.0

then that gives

  • 50 x 1 = 50
  • 20 x 2 = 40
  • 20 x 0.5 = 10
  • 8 x 0.5 + 8 x 1 = 12
  • 3 x 0.5 + 3 x 0.5 = 3

or 115% i.e. systems with distant binaries (c. 20%) and systems with triples (c. 8%) have a chance of two goldilocks zones thus increasing the chance of one of the zones having a suitable planet.


How Many Stars of Each Type?

  • 3% F, blue to white
  • 8% G, white to yellow
  • 12% K, yellow to red
  • 75% M, red
  • rest, various giants

Assuming red dwarfs (too cold) and the bright giants (not enough time) and red giants (exotic exceptions) don’t have habitable planets and some of the F, G, K stars are too young (especially F) that gives us about 20% of those systems which have stars with a goldilocks zone that may have lasted 3+ billion years.

So in an 8×10 parsec section of space you’d have 40 star systems and c. 8 with stars with viable goldilocks zones – multiplied by the bonus from binary systems say 8-10.


How Many Planets?

Since 2011 (iirc) the Kepler telescope has been off looking for planets and apparently there are a lot more than originally thought to the extent that assuming 2-12 per system is plausible so if a star has a goldilocks zone then there’s likely to be at planet in it.

What other conditions are necessary?


The sciece of planetary formation is still largely guess work so I’m just going to go with what I find plausible from my reading.

I’m going to say that gravity is one of the core conditions which is a function of mass and density. Simply put say you need gravity in an earth-like range to hold the right size of atmosphere. Too low and the atmosphere is too thin and it’s too cold. Too high and the atmosphere is too dense and it’s too hot. So, say you can have

  • small, medium and large planets


  • low, medium and high density

and say the chances are all linear then the combinations of

  • small size, high density
  • large size, low density
  • medium size, medium density

might all give gravity in a 0.75 to 1.25 g range.

(Effectively this would replace the “size” roll in the Traveller world gen with a “gravity” roll.).

On a 2d6 roll the gravity table might be something like:

  • 2-5 = low gravity, either rock planet with no atmosphere or frozen atmosphere
  • 6 = low earth gravity
  • 7 = standard gravity
  • 8 = high earth gravity
  • 9-12 = high gravity, dense oven atmosphere

so rolls of 6, 7, 8 would have the right gravity to retain the original CO2, Methane, Nitrogen etc exotic type atmosphere and for that atmosphere not to be too hot or cold for life to start and for that life to gradually oxygenate the original atmosphere over time.

So of the 8-10 systems with planets in the goldilocks zones of the right kind of star that’s roughly 50% with gravity within the right range to retain an atmosphere i.e. 4-5 per 8×10 parsec area.


Using the above table you’d then specify the 2-5 rolls as trace atmosphere, 9-12 as exotic and only roll for the atmosphere of the 6-8 gravity planets.

Following the current theory of how the atmosphere developed on earth, this atmosphere roll would really be about how long the original exotic atmosphere has been transforming itself.

The general idea is life starts at the bottom of the sea where microbes develop to feed off stuff coming out of volcanic vents and these microbial organisms excrete oxygen. So the four stages of “earth-like” planet are

  • stage one: exotic atmosphere, very high radiation (no ozone), dead land, exotic sea, microbe life at bottom of sea
  • stage two: exotic atmosphere, high radiation, dead land, oxygenated sea, sea life
  • stage three: thin breathable atmosphere at low altitude, exotic elsewhere, medium radiation, teeming sea life
  • stage four: standard atmosphere at low altitude, thin elsewhere, low radiation, life starting on land
  • stage five: standard atmosphere, background radiation, life everywhere

Say the table is (2d6)

  • 2-3 stage one
  • 4-5 stage two
  • 6-7 stage three
  • 8-10 stage four
  • 11-12 stage five

A planets at stage one is are not much better than a lifeless rock. Stage two and three are not great but preferable for a stepping stone colony than bare rock. Stage 4 and 5 would be the prime we the prime colony sites.



The current theory of how a breathable atmosphere arose on earth starts with the right amount of gravity and lots of liquid (hence the importance of the goldilocks temperature range so the liquid doesn’t freeze or evaporate).With the atmosphere being mostly CO2 the liquid is initially carbonic acid which eventually leads to underwater microbes who oxygenate into water. If we follow this theory it means that if we assume a breathable atmosphere it must have water (or must have had water in the past).

So the hydrography percentage means different things depending on the previous gravity/atmosphere rolls.

Roll 2d6-2 (x10) = 0% to 100%

  • for the planets with low gravity and trace atmosphere the percentage is frozen vs rock
  • for the planets with too high gravity and exotic atmosphere the percentage is liquid something – the something depending on the type of atmosphere

for the planets with standard gravity

  • for planets with stage one atmosphere it’s the percentage of exotic liquid. if 0-2 then life may have stalled or slowed
  • for planets with stage two atmosphere, assuming the process requires water, it’s either the percentage of water or the percentage that has been oxygenated. if low, say oxygenation has only happened around the edge of tectonic plates (volcanic areas)
  • for planets stage 3 or above it’s the percentage of water. if 0-2, assume planet terra-formed itself too slowly and the star’s goldilocks zone is moving past them so the planet is becoming too hot. (given the default theory this would be how a tattooine type planet developed i.e. it *had* oceans in the past to oxygenate the atmosphere which have since dried up



The end result of thinking this through again is close to what I had before except

  • I thought I probably had too many “earth-like” planets but with the Kepler data I think that number is quite plausible (where “earth-like” doesn’t mean like earth now but planets that are part way through the terraforming process)
  • I think i had too many planets that had reached the final stage because i was thinking if a star has been around 10 billion years and we’re assuming it takes 3+ billion years for a planet to go through the process then old stars should have more chance of an earth-like planet but this isn’t the case if the goldilocks zone moves – if it moves then the age of the star is maybe not as important.

So, more part way earth-like planets but fewer late stage earth-like planets.


Great Filter

The argument against lots of planets with life is the Fermi Paradox. Given the huge number of stars and (now known) the even huger number of planets, to explain it you (mostly) either need a single great filter or a long chain of small filters (collectively making a great filter) that make life a one in a trillion outside chance.

This would make space 99% airless rocks – not fun.

However I think a plausible great filter is the shifting goldilocks zones – say a system where the second planet out is in the goldilocks zone for 3 billion years but in the time it took to get near life on land the goldilocks zone has moved and the planet gets too hot. Then the 3rd planet out starts to develop life but  after 3 billion years but just as it nears life the zone has moved on again and then the 4th planet and then the 5th. So after 12 billion years the star system may have *almost* completed the process of developing an earth-like planet 4 times. And then the star blows up.

What this would mean is the first species to get into space could find lots of planets that are *partway* earth-like and they could speed up the process (and maybe eventually slow down the sun so the goldilocks zone didn’t move again).

So not all airless rocks – although even the part way terraformed ones might still be mostly lifeless except under water. In a lot of cases colonists would need to bring their own flora and fauna.


Gas Giant Moons

As well as standard planets a potential second possibility for “earth-like” are large moons around gas giants.

Gas giant moons are apparently liable to be warmed by tidal warming which might mean they could exist not just in the goldilocks zone but possibly out some way into the otherwise too cold zone.

The gas giants we know about have lots of moons.

Tidal warming is proportional to how close the moon orbits the gas giant so if they were in the warmer part of the goldilocks zone they’d need to orbit far from the gas giant and if further away from the star they’d need to orbit closer.

Assuming an average size smaller than standard planets and

  • size is small or medium


  • density is low, medium and high

and out of the various combinations only

  • small size + high density or medium size + medium density

gives standard gravity then the chance is lower than standard planets (which had the large size + low density option also.)

Then we have:

  • lots of moons
  • some of the right size
  • needing to be in the right orbit of their gas giant
  • their goldilocks zone possibly extending past the star’s goldilocks zone into the too cold zone

so a second chance at an earth-like planet in a suitable system and a small chance of both.






Continuing with the theme that a good scifi game is one that supports the kind of scifi a person likes. In my case that’s sciency space western where the sciency stuff isn’t the point but it’s necessary to create the right scifi *feel*.

Sciency Space

I’ve written about this before but as this blog is mostly a notepad for my projects then as things change I’ll make new posts and delete or compress older ones.

Colonization Premises


Premise: Colonist Type

When people think of space colonization they often think of earlier episodes like the US frontier however space colonists are more likely to be technical specialists: engineers, scientists, technicians, a space colony’s farmers are more likely to be running half a dozen biodomes than two mules and a plow and space miners might be sitting in a pressurized cabin watching half a dozen mining drones.

So i think space colonization will be different because of the type of people involved.

Apart from Homo Astralis who want to go into space because it’s there the other main group of potential colonists will be people who want a better life but if space requires technical skills and technical skills generally lead to a decent life on Earth there’s a Catch 22. Only if life on Earth become much worse for the sort of people suitable to leave will there be a large candidate pool. This might happen of course but otherwise i think permanent space colonization will mostly be undertaken by relatively small numbers of a particular type of person.

There are possible exceptions – space Amish, political dissidents, criminals etc but otherwise I think this will generally be true.


Premise: Trade and Resources

There’s an argument which seems plausible to me that even with FTL, interstellar trade in common resources doesn’t make sense because each solar system has a more or less limitless abundance of those resources so lots of scifi troops space miners and ore freighters maybe but only in-system and not interstellar.

I can see some exceptions to that – low cost extraction in one system outweighing the transport costs – but otherwise i think i agree.

This idea particularly effects a lot of older SF where mining colonies are almost the default.


Premise Colony Type

I think colonization of the solar system will follow traditional logic so initially exploration and knowledge for it’s own sake but eventually also resource extraction. Most people wouldn’t want to raise children on an oil rig but if the money is good enough people will work on them for a time and then come home to their family. People would go to work on space rocks on the same basis.So if scientists and explorers lead the way to figuring out how to live on space rocks then commercial colonization will follow to extract resources (even if only for n years at a time in the same way oil rigs are only months at a time).

However what about beyond the solar system?

Personally, with or without FTL, I can’t see many people wanting to permanently colonize and bring up children on a space rock where they couldn’t survive without external tech support – some but not many. If there was enough money in it maybe but then they’d want to earn it there and then leave to spend it somewhere nice.

The other option is people being forced to do it but scifi is high tech so even if they were forced how many people would you actually need on a space rock?

So personally I don’t think you’d get large space colonies anywhere that didn’t have the potential to turn into a “Home” world i.e. a breathable atmosphere and the possibility of survival in the event of external tech support being lost. The keyword here is “large” – a colony that could eventually turn into another Earth. There’s still plenty of reasons for small ones.

There are plenty of conceivable exceptions to the rule but I think it would be the rule.


Premise: Conclusion

So my space colonization premise is permanent settlers would rank target planets in terms of their pleasantness and survivability without tech:

  • type one: breathable atmosphere, native food resources available using lotech methods if necessary – fully tech independent
  • type two: as above but some kind of taint e.g. too much UV, insects, pollen etc which makes life outside domes unpleasant but not lethal and can be adapted for in clothing etc
  • type three: non-breathable atmosphere but with plentiful components for making fresh air and water and with native food resources e.g. planet where the oceans have life and oxygen but not elsewhere
  • type four: non-breathable atmosphere with plentiful components to make fresh air and water and grow hitech food
  • type five: fully dependent on recycling or outside supply – fully tech dependent

and only type one could get significant numbers of voluntary settlers and that number would be reduced by the need for relevant hitech skills.


  • population growth could be fairly slow and steady in a hitech colony assuming the female colonists don’t have 16 kids
  • space Amish or forced relocation of settlers only equipped with seeds and basic farming tools could grow faster
  • maximum reachable population would depend on rank – even second rank colonies would have a low (voluntary) size imo.
  • after a tech collapse a type 2 or 3 colony could go native and expand naturally to its lotech limit.
  • a colony that developed it’s own resource extraction and manufacturing base to the point where it was tech independent could negate the survivability issues but I don’t think a colony is likely to become large enough to do this unless it was attractive to start with.


In the past my mental picture of “sciency space” (assuming FTL) was mining colonies everywhere with some growing to become independent polities but that doesn’t work for me any more and now “Sciency Space” has to revolve around the systems with Earth-like or nearly earth-like planets. There can be hundreds of exceptions but they will be exceptions to the general rule so for example in an Imperium sized bit of space there might be one system with billions of people living on a hell world (or something similarly unlikely) but not dozens.

The biggest exception to this rule would be if the setting has FTL travel with some kind of range limit in which case there would be stepping stones along the route to the earth-like planets.

So how many systems have earth-like planets?

More rambling on this as it’s interesting and I realise this is what I’ve been trying to do with Traveller for a while – inject a more sciency feel.


Recapping – if we accept as a premise that a good game is a series of interesting decisions and that good sci fi is either speculative-science fiction or space fantasy with enough science to *feel* sci fi then what’s a good sci fi RPG?

I’d say

  • any RPG, not necessarily sci fi, with mechanics that can make non-combat encounters into a series of interesting decisions applied by the GM to a speculative science plot
  • any space fantasy RPG where the GM sprinkles enough bits of science into the mix to give it that sci fi feel


Just a List

A list of what and where to sprinkle from the top down. Some games will already have some of these and others won’t – for each category scavenge what is best from each..

Sciency Space

Instead of just space or star system also have nebulae, proto-stars, brown dwarfs etc

Sciency Star Systems

Binaries, anomalies, odd hazards, colonies of colonies, intra-system conflict

Sciency Planets

Gravity, atmosphere, orbit, climate, evolved species

Sciency Colonies

some mundane, some exploring sci fi social tropes

Sciency Space Travel


  • realistic and STL
  • handwavium and ignored – taxi service
  • handwavium but with rules and complications – fuel, maintenance etc – which buries the handwavium in practicalities which in themselves are sciency

Sciency Combat

sciency weapons, equipment, environments

Sciency Plots, Maguffins and Chrome

Have chrome that reinforce the feel e.g. instead of just mundane trade goods add sciency things that reinforce the setting to the list like: life support cartridges, greenhouse parts, fuel refining plant, ice processing plant, water purifiers etc and/or planetary exotic trade goods like Regina Wine, Karelian Bluewood etc.



Sciency Space / Systems / Planets

Size of setting and speed of travel is important here. If you want a giant empire then the number of systems will be too large to detail however if back story specifies only the best systems get fully colonized then you only need to do those systems and any stepping stones in between. The rest can be done as and when needed.


If you make nebulae block FTL then you can use them to create interesting geography – a system might be tucked away inside a nebula only reachable by a complicated route – perfect for some secretive group.

2D vs 3D

If you hand wave that jump technology uses 5D geometry then you can treat a flat 2D star map as a projection – like Mercator’s – so the star positions are correct for jump navigation and a STL star map including the z co-ordinate would look different. I think that’s a reasonably neat way to ignore the z coordinate if you don’t want the hassle.


Sciency Combat
  • core is a series of interesting decisions
  • don’t need lots of weapons doing the same thing
  • make each have a tactical cost/benefit e.g. long vs short range, zero g, powerful but slow firing etc
  • exotic weapons can be situational or non-lethal: shock rods, web tanglers, tranquilizer darts (or poison)
  • tactical gadgets, sci fi armors, combats in sciency environments
  • low health, high damage, high armor



In the first part I focused on what I think is the traditional core of sci fi which is the kind that revolves around science / speculative science. A lot of people would say this was the only real or good kind of sci fi and the rest is space fantasy. Maybe they’re right but that just shifts the question to “what’s a good space fantasy rpg?”

Space Fantasy

I’d say any that provides the kind of combat / game play you like. If you want space combat for example and either fighter combat or big ship combat or both then your RPG would need to have that. If you want to play a Firefly type game then you want one that’s put some thought into their trading rules.

Star Wars is a good example of space fantasy as the underlying science is mostly irrelevant to the plot and it’s generally not even sprinkled on as a veneer.

However I think there’s a hybrid category in between core sci fi and space fantasy which is “sciency” space fantasy and that’s what I like.


The Expanse

A good example of what I mean by “sciency” space fantasy is The Expanse. I’m sure there are plenty of unrealistic things in it but they sprinkle enough realistic feeling tropes to nail the sci fi *feel* imo. For example in the first episode:

  • zero g
  • magnetic boots
  • ice mining for air and water
  • physical effects of low g on body
  • cramped space – people going stir crazy
  • advanced medicine, prosthetics
  • effect of high g planet on someone adapted to low g
  • high g manouvers

and probably more.

The underlying plot is basically a space western; it could be ranchers, herders and miners (Mars, Earth and Belters) fighting over a water supply but by thickly layering sci fi elements either as sub-plot points or simply window dressing it delivers that sci fi feel – not a deep exploration of a single trope like core sci fi but an adventure plot that hat tips lots of them.


What’s a Good “Sciency” Space Fantasy RPG?

I’m not sure there is a single one and if there is it’s probably single system and STL but i imagine most have something that can be scavenged for this purpose – which you can add yourself.

I think that’s generally going to be the case – take any space fantasy rpg you like and sprinkle sciency bits in yourself. Take each aspect of your game universe that feels too hand wavy and through scavenging movies, books, documentaries, other games etc replace the hand wavy bits with some speculative or not so speculative sci fi and/or make your standard game plots revolve around something sciency – for example:

– make the speculative science behind your FTL have inconvenient practical consequences in game e.g. related to fuel, which make it feel more grounded in reality

– if the game has artificial gravity for ships think of other ways of getting the players into zero g situations e.g. make the expensive part of artificial gravity be a component that is built in to jump drives so it’s very expensive for non starships so in system ships use rotation or make the artificial gravity malfunction at dramatic intervals

– if life support is hand waved as some kind of plug in modular system like large printer cartrifges then use that somehow – like extracting the h2o from spare life support modules to put out a fire or some kind of rodent getting into a food cartridge. separate short term ship life support from long-term colony life support requiring oxygen gardens with cartridge modules just for emergencies

– make journeys with repair and maintenance into a part of game play e.g. a free trader or exploring type game includes a process where where hazard type encounters cause players and transport to lose a form of HP in the shape of stress and strain which requires decisions over resource management and R&R

  • have sciency star systems, planets, atmospheres, climates

– if the players are recruited to hunt a weird species then make the planetary conditions a plausible source of the creature’s evolution

– make energy weapon combat have heat related consequences



Part 3 – just a list

Although I like listening to people talk about “What is Sci Fi?” I’ve never really cared what the answer was – I just like what I like.

However I watched a couple of youtube vids which touched on / extended the question to “What is a good sci fi RPG?” (which i’ll extend to games generally as i’m currently mostly messing with board games) and this made me think about the subject more as “what is a good sci fi game?” is built on top of “what is (good) sci fi?”

The two vids were:






What is (Good) Science Fiction?

The original core of it is hinted at in the name “Science Fiction” and more so if you include the other name it often went by in the past “Speculative Fiction.” If you join the two with emphasis added to stress the point you get “Speculative-Science Fiction” i.e. fiction based on speculative science.

I think most classic science fiction from Frankenstein onwards has that – you take some aspect of science or technology, extend it into the future and then speculate about some of the possible logical conclusions. This doesn’t have to involve space at all e.g. genetic engineering, extreme longevity, AI, robots etc.

If it does involve space then it either means STL ships and speculating on the logical consequences of that e.g. generation ships, sleepers etc or some as yet impossible FTL travel – and the logical consequences of that.

It doesn’t have to be focused on physical science either – it can also revolve around the social consequences of science / technology


Speculative-Science Fiction and Games

Given this definition a good Speculative Science game might be a game that provided a solid platform for a kind of “Trope of the Week” type of gameplay. The rules would be fairly generic as each episode would revolve around some issue caused by a different trope and the solution of that issue would depend on the particular trope.


Trope of the Week Design

This could be designed

  • around creating a series of one offs with different, probably pre-generated, characters facing a different trope each session like a separate movie
  • around the platform of an episodic series where the same characters travel around bumping into examples of particular tropes.

Some examples of the latter design might be

  • Fallout: surviving vaults that went down different paths coming out and creating wasteland towns based on some social concept or other, the players are part of a caravan traveling from vault to vault
  • Traveller: a human imperium collapses leaving the isolated colonies to evolve in different directions, similar to the above except the players are in a space ship and the physical planetary conditions could drive the social concepts or add physical adaptations
  • Star Trek: as above except unexplored space so using aliens as proxy humans
  • Others: Stargates, Timeslips etc

So once you have the platform that allows players to bump into a series of “trope of the week” encounters then you need your list of tropes to encounter.


The GM would mine existing sci fi movies and books for a concept and then build a game session or mini campaign around one of them at a time.

However there’s a problem.


Sunshine is one of my fave sci fi movies and i think it sits squarely in the realm of speculative science fiction i.e. the speculation is the sun is dying and the team set off to fix it. Now whether this is *plausibly* scientific or not, I don’t think matters, it’s a sci fi premise and makes people think sci fi thoughts about stars, God, survival etc.

It also tries to have a realistic feel – at least in the sense of what people today imagine to be realistic when it comes to space flight – which i think helps to reinforce the speculative part.

Some of those elements are:

– fragile spacecraft: unless building them in space, everything has to be lifted from the planet hence minimum weight is an issue

– sling shotting to reduce fuel

– shielding: radiation, mini asteroids etc

– resources: DIY oxygen with plants

(apparently they had a clever explanation for the artificial gravity but it didn’t pan out hence the lack of spinning)

So if Sunshine is good sci fi (imo) how would it do in a standard sci fi RPG game?

Not that great in my experience.

A Series of Interesting Decisions

One well-known definition of a good game is “a series of interesting decisions.” That may not be a 100% perfect definition but it works for me.

(This is why imo combat encounters are such a big deal in RPGs as combat naturally provides lots of decisions in a dramatic life or death context. As well as the tactical decisions there’s also the resource management decisions with the players managing wounds/health/hit points and maybe limited special attack types or equipment.)

However in most speculative-science fiction there is little or no combat. It’s often very talky, often almost a science detective game and the non-combat obstacles generally involve journeys, mishaps and either repairing technology or manufacturing special technology.

If you picture the events of Sunshine as RPG encounters most of them are either social interactions or repairing stuff and most sci fi RPGs will have character skills for social interaction and repairs so most of the dramatic events of the movie would boil down to a few engineering skill checks.

Some game types can get around this easily – like a first person sci fi RPG where if you need to go outside in your space suit to fix something the game can make navigating around your ship via little puffs of air into a risky mini-game.

So I think turning speculative-science non-adventure sci fi into a game requires turning whatever their equivalent of combat encounters is into an alternative form of drama involving a series of interesting decisions.

(For example a lot of sci fi involves a journey to the boss encounter and one way to make it more dramatic might be to copy the “The One Ring”‘s idea of a journey as a kind of resource management process. Various mishaps on the journey and the player’s characters success or otherwise at dealing with them, as well as possibly losing NPCs, equipment etc along the way, add to a cumulative “strain” score which affects how prepared the players will be for the boss encounter at the end.)


I don’t know if there is a sci fi rpg like this but there are probably social / narrative / detective type RPGs which have interesting mechanics for the social interaction / NPC malfunction part and maybe mechanics for non-combat encounters which can be reworked to make things like repairing stuff more dramatic so probably the best bet for a game like this is find one of those and add the sci fi.

I’d guess an actual game book based on this idea would be light on rules and heavy on examples of book/movie plots reworked into game sessions.



“I’ve done one-shots similar to stories like Sunshine. True, there may not be a lot of combat in a game session. I treat combat as I do any other skill. And not all characters will have such a skill. So other skills are made use of instead of combat.”

Yeah, i’m not saying it can’t be done with standard RPG rules. I’m mostly wondering about how non-combat mechanics from other games might be applied to space journey type situations.


Part 2 – Space Fantasy