This is not an exhaustive listing of all the types of science fiction, but some hopefully focused rambling on what considerations one might have in a science fiction setting. It is focused mostly on thinking about things in terms of tabletop role playing games, but probably applies more broadly to fiction as well.

One possible approach is to look at large setting elements (things like aliens, spacecraft, space travel, cybernetics/transhumanism) and decide how you want to deal with them. This has nothing to do with the rules one is using, at least not directly: if you wish to make a SF-flavoured Dungeons and Dragons, it is extremely doable. So we will talk in generalities about some options for some of the big questions, and how they might be addressed. If one wants a whole book, with worked (instead of illustrative) examples, check out GURPS Space.

To jump to pontifications about a specific topic, click any of the following links:

• Aliens
  • Mutants
• Travel
• Communications
• Ships
  • Scale
  • Ship Combat
• Biotech and Cybernetics
  • Fast Healing
  • Life Extension Treatment
  • Cybernetics
• Conclusions

Aliens

Presence of aliens is a big question for a setting. Are you going for:

• The Star Wars Cantina with a bunch of weird aliens, all different?
• John Carter with a couple of well-defined aliens?
• The Thing or War of the Worlds with one (type of) alien that is mostly a mystery that is never fully explained?
• Star Trek with rubber-forehead aliens that are still largely human?
• Firefly-ish with no hint of (sentient) aliens?

Of course, other variants on this exist: Battlestar Galactica has one “alien” species in the form of the Cylons but is mostly human, with Cylons and humans being bitterly opposed. If you want to have the aliens, then you need to come up with some means of adjudicating them in a game. All the PCs being humans makes it a little easier, since you can reskin normal monsters: need a small grey alien of some kind? Use your ruleset’s way of representing “an goblin” and change the description. Need a big hulking Chewbacca? Redescribe an ogre or something similar.

Player-side aliens are more constrained by rules, normally. If the aliens just have rubber foreheads, then it is about the culture of them, so just put some effort into that (which you should be doing anyway, even if just to detail how you can challenge them to a duel of honour or something). The actual rules will just be normal humans with green skin and unusual ears. Maybe they get a small bonus to strength or are able to see in the dark. Which is almost like a re-skinned B/X class or something: space dwarves, space elves, space halflings and so on all work (just look at Starfinder for a literal example). Note that the important part is the stats, not things like being short or having pointy ears or big feet: a B/X dwarf is tough (from good saves) and has some innate abilities to figure out slopes and similar things, and being able to see in the dark. Sure could be an alien….

The amount of effort required is going to depend a little on where on the spectrum of how common aliens are your setting intends to be. More aliens are not always more better, because you can end up merely flattening them out, but having more means that you (possibly) want some rules for how each one works: if an alien has an electric attack or five arms or similar, some thought as to how to deal with that should be given.

Androids and Robots

Using these is really a means of making social commentary about the ethical or otherwise use of a specific class of people as labour. That said, sentient robots and androids are common in many settings, but in terms of rules, they are just aliens: if they are non-player-facing, then use whatever statblocks make sense, if they are a player option then they probably have some abilities related to being stronger and tougher than average humans. They likely have some hindrances in terms of needing to be subservient to humans or some other sort of brakes on them.

Mutants

These are essentially just aliens, and the same sort of things apply: non-player-facing ones can just be redescribed from the normal monster books. Player-side mutations are possibly discrete abilities, but if there are “standard” mutations then they could just be treated as species/races/ancestry, as your ruleset dictates.

Artificial Minds/AIs

These are also a staple of many settings and can be treated a few ways but can often be treated as an alien. If one wants to have the sort of over-arching controlling type of AI, that is often more of a background element that does not need specific rules but is something that is a background setting element. There are of course a few different ways that this might work out, but most examples are on the dystopian end, with two common variations:

• The AI is able to do its task, but that task is mis-interpreted and the AI decides that (some? all?) humans are a threat to be dealt with.
• The AI exists but is unable to effectively oversee everything. This will usually mean that the technological government is somehow hampered or has gaps in control or similar places for characters to exploit.

In many cases, these are just the local government: interactions will be with robots or drones, or various people employed by the AI. Having a large-scale AI in the background often comes down to how a government is themed: routine paperwork can just be done via the ‘Net by talking to one of the AI’s nodes instead of a distinct person. This might just look like a very tightly integrated bureaucracy or similar.

There are relatively few examples of powerful benevolent AI entities, largely because they fall into the “why is this powerful entity not just solving their own problems” quite often. This means that they need to be constrained or weakened in some way to provide reasons for the characters to be doing things instead. They can also be placed in opposition to equally or more powerful less benevolent AIs, which ends up looking a lot like a feuding pantheon of gods (vide: Horizon: Zero Dawn’s conflict between Hades and Gaia for a very unsubtle example). Iain M. Banks’ Culture has some of the best examples with the Minds, although they do turn up elsewhere.

Player-side AIs are often just tools that handle things like translation, research, and targeting (providing bonuses to doing those things). Players actually being AIs loops back to them being an alien of some kind, depending on the body that the AI is using and what that behaves like.

Travel

The ease and speed of travel can be an important pacing and setting element.

• IRL, we have space travel, but it is slow and extremely limited, taking potentially months or years to move between planets. Interstellar travel seems infeasible.
• The Expanse has fairly free travel within the solar system, but still considers time to be an important restriction.
• Traveller has all travel between systems taking about a week, with travel in a system usually being hours or a day or two.
• Star Wars just ignores travel time and in many respects even distance, although some of the novels and games put a little more thought into it.

This largely impacts two main areas of the setting: scope and speed.

• Scope is fairly self-evident:
  • Star Wars has an entire galaxy to play with, because travel is so abstracted
  • Traveller has a large interstellar empire covering a few hundred parsecs along each edge of the map
  • The Expanse is limited to the (mostly inner) solar system
  • The War of the Worlds (and many, many other SF things) is limited entirely to Earth
• Speed is not quite the same as scope, although it is oftentimes linked.
  • Star Wars ships move at some indeterminate speed (the speed the plot demands, really) so travel is fast and mostly glossed over. (Although getting into hyperspace can be dramatic, normally once travelling things “just work”.)
  • Traveller ships take a week to make a jump, meaning that there is potentially scope for interactions during travel from one system to another.
  • Other settings might make travel dependent on the distance being travelled, but they might still be covering vast gaps in hours or days.

The importance of these is twofold: larger scope means that there is more chance to get lost in the black, exploring or travelling to all sorts of strange places and meeting the strange people (aliens?) that are there. Troubles can plausibly be left behind by going a few systems over and hoping that no one follows you. Faster speed means that those distant places are easier to get to (leaving aside things such as cost of travel and actual availability of ships, of course). This might have the effect of making the scope feel smaller. Star Wars has a whole galaxy to play around in, but the movies never give much of that sense of scale because the characters just bounce around as needed.

Running a modern day game as an analogy, the scope might be the whole planet, but travel is fast: you can get pretty much anywhere in three days or so using commercial air travel and modern motor vehicles (albeit with sufficient preparation). Having your own aircraft might make it even easier, assuming one can arrange the legalities and so on. In a late 1800s game the scope is the same planet, but travel is much more arduous and slow. To get from Australia to England is at least a few months in some of the fastest sailing ships devised. Getting to somewhere remote and inland like Mongolia from New York could be months of overland travel as well as a few weeks on a passenger ship.

The interplay between these can enrich a setting in various ways. Traveller has relatively slow speed, emulating an age of sail sort of mentality: the people on the ground must be trusted to handle whatever the thing on the ground is because any actual help is days or more away, just from travel time. On the other hand, quick travel will facilitate having a group of characters acting as troubleshooters who get into a place while the problem is still developing.

Communications

Similar to the speed of travel is the speed of communication. Fast communication will allow for greater centralisation or at least the possibility of it. When it takes weeks to get a message to the head office and back, then the message needs to be very detailed because any back and forth is costly in terms of being able to actually act on the contents of the message. This also leads to the people on the scene needing to be trusted (and given the authority) to solve problems without reference back to that head office.

Fast communication can lead to the opposite. If it is easy to phone home, then there is greater impetus to do so, and check in on bosses (or juniors) and make sure that they are doing things correctly. Star Wars features this, although it is not entirely reliable, being possible to jam signals or otherwise prevent things. BattleTech has the Hyper-Pulse Generator network that can send messages within a certain range instantly, but is offset by being expensive. This means that news and events in both settings travels much faster than something like Traveller, where the news travels at the same speed that people can.

Another consideration is that individual systems may have an equivalent of the internet or similar networked information and communication. However, with slow communications these system networks will not necessarily be up-to-date with nearby systems due to the delay in sending new information¹.

Ships

Of course, one need not actually have viable spaceships for a science fiction story, but many will have them. The ships in use (or not) can truly define a spacefaring setting:

• Star Wars (and numerous settings, vide: Battlestar Galactica, Wing Commander as good examples) has them work like WW2 naval combat: large slow ships and small nimbler fighters
• Firefly and early Traveller (amongst others) has them acting more like small seagoing vessels, tramp traders and such.
• The Expanse has different sized ships but they are not as clearly-cut as “carriers”, “battleships” and “fighters”.
• (Early) Star Trek has pretty much one ship, with the adventure being on the planets she visits.
• Stargate just does not bother with ships at all, using the titular Stargate to move from (forested) world to (forested) world.

When looking at how ships should behave, it can be useful to think about what they are intended to do. Are they merely a home-base for exploring strange new worlds? Are they the means of communication, but not combat? Are they primarily military in nature (or at least all armed to some extent)?

There are a few roles a ship in a SF RPG can play:

• A home base for the PCs (or for others): Classic examples are things like Battlestar Galactica, Star Trek, Firefly
• A threat to various places and people: Star Wars’ Super Star Destroyers, Firefly’s Alliance naval vessels
• A source or sink of value or effort: Classically, Traveller ship loans are pretty punishing.

It is also worth mentioning that even if ships are present, that does not mean that the characters are required to have ready access to one. There are numerous SF stories in which characters have no ship (or no control over the ship they are aboard): Dumarest, some eras of BattleTech, the non-command crew in Battlestar Galactica, and more.

Scale

Part of this comes down to the scale of the ships in question. Something like an Imperial Star Destroyer or a 40k Battleship or similar can sometimes be too big to be satisfying in a game, unless the characters are in charge of it. Otherwise you are forced to just go along with wherever the ship goes. This can be fine for certain things, but if the goal is to have the characters be starting small, then having the ships they are dealing with be so large can lead to mixed expectations. At the same time though, if ships are expected to be this big, then if small ships are common, then large ships can become simply plot devices. This is used to fairly good effect in Firefly: the Alliance Navy suddenly showing up in a big ship is a big moment, not a routine encounter, so it might not even be something that needs to have in-game stats beyond “You Lose”². A single X-Wing is not really going to be a major threat to a Super Star Destroyer, but might be able to knock out a few components and escape, so only those components need to be detailed.

On the other hand, having a setting with all the ships being similar in size and capability means that at least one-on-one anything that the characters encounter are possible combat encounters. It also means that either ships are common, or they are uncommon enough that even planets and formal powers in the setting are limited to the same technology. This might often be the case in a frontier setting or something otherwise relatively low-tech (or at least even tech for everyone).

Ship Combat

Another consideration is whether ships are routinely armed, and what with. If ship-to-ship combat is routine, then most ships will have some sort of weapons and armour. This also implies that repair and resupply of ships is equally routine, and not too costly. As a consideration for RPGs, destroying a ship outright is very likely to lead to a total party kill, which is probably worth avoiding³.

Should ships be expensive and largely unarmed, then ship-to-ship combat will likely be deprioritised, focusing instead on boarding actions and captures that do not risk the vessel itself being overly damaged. This is the model used in some of the eras of BattleTech: there are no WarShips, and JumpShips are expensive and rare due to inability to really build more at scale for the setting. Battlestar Galactica does the same thing: losing even a Viper fighter is a major issue because the fleet has no real way to replace them, let alone any of the other ships of the fleet. The original Star Trek was even more limited: there is only one ship for the most part, and so it is irreplaceable. In the case of BSG though, combat is still expected, and part of the story is the attrition of resources over time, which also often holds for various RPGs. How this is squared with possibly destroying the vessel should be considered though. When ships are rare and irreplaceable then should they be damaged or destroyed the story will usually need to switch to a different sort of mode: the shipwreck or similar. Rare ships and shipyards also suggest that getting parts and doing repairs may well be an adventure in itself.

Biotech and Cybernetics

This covers a wide range of things, so this is even more general than most of the waffling above. A really useful thing that these can do though is allowing characters offset bad things from character generation or consequences of their actions.

In all cases discussed in this section, there are two common axes:

• Ubiquitous and cheap vs rare and expensive
• Weak vs powerful

Fast Healing

One of the common things in SF is advanced medical abilities. This can cover a range of things but some examples of how it can work includes:

• Stars Wars has bacta tanks for handling serious injuries
• the Vorkosigan books have cloning of body parts that are used in surgery
• Various drugs may exist to speed up metabolism or similar things
• Prosthetics are common in various settings (Star Wars, The Expanse, many of them)

Fast healing will reduce the effect of combat, at least in cases where characters survive a fight in the first place. Not having this is going to make things more dangerous and less attractive.

Even if fast healing is available, that does not mean that it is affordable. For example, The Expanse has cloning for folks on Earth, but Belters are largely limited to mechanical prosthetics.

If fast healing is powerful but rare, then it is an adventure to obtain it. If it is ubiquitous but weak, then it will be everywhere, but less game altering. Having it be ubiquitous but powerful leads to cases of people being very difficult to kill permanently. Rare and weak fast healing means that injuries will mostly just heal naturally, making for things to be more dangerous.

Life Extension Treatment

This is somewhat common in various settings, but is usually more of a Macguffin than something that has real in-game effects. These will often be expensive or otherwise very restricted. How they work can vary from cloned organs (Vorkosigan), special drugs (Blue Planet, Traveller), brain transplants into clones (Vorkosigan again….), and other things. That said, because most games do not care about things happening over years, this is not usually something that is more than a resource drain.

Cybernetics

Most of these are just special abilities and can simply be treated as such: letting a character be able to jump twice as high because they have springheels or see in the dark using their infra-red implants is fairly easy to actually implement. One thing that should be considered is connection to the ‘Net, which can affect attempts to isolate characters. This should also be remembered as an ability for other characters to call for help or similar.

Additionally, things like implanted recording devices can affect providing evidence of activity (both by player characters and various others). This is obviously useful for law enforcement, but might also be spoofed or otherwise faked.

Ubiquitous but weak cybernetics might mean that most people have an implant to connect to the ‘Net and possibly that prosthetics to return baseline functionality are common, but you are not going to be seeing full-body replacements or advanced combat implants much. Ubiquitous but powerful cybernetics is going to end up with supersoldiers on every street corner. Rare but powerful cybernetics means that there are folks wandering about with advanced combat implants, but those are going to be scary and important people, not the folks you just randomly meet on the street. Rare but weak cybernetics are sort of our real-world baseline: sure, you can get hardware implanted, but it is not really going to be able to do very much.

Some settings will have cybernetics but done through biology: wetware, not hardware. The same sort of things as for cybernetics apply to wetware, it is just that instead of putting electronic eyes in it will be some sort of custom-grown eye or an equivalent organ.

Conclusions

As mentioned, this is absolutely not a comprehensive way of approaching how one might define SF settings, but I think that it is a moderately useful one, especially for space opera. This does not address themes, or rules, or societal customs in a setting, but by playing with the levers, one should be able to make a functional and interesting SF setting to have players do stuff in.

Should anyone use this framework thing to make a setting, please reach out on discord and let me know. I will probably be doing exactly that for the hell of it anyway, and if I do I will post the results here. Equally, should you have a different sort of breakdown of SF elements and how you use it, please post it up!

Edit [2026-07-17 11:55]: Added some thoughts on androids and AIs.