Yes, most of these are from Star Wars. This really shouldn’t come as a surprise to anyone who has been reading my stuff for a while. Hyperspace Opera is primarily going to be a Star Wars remix with some alternative ideas thrown in and a different focus.
ITL was developed as a simple and elegant solution to enable easier communication between space ships and inside space ports. It is a fairly straightforward language with simple grammar and single letter based writing system. What makes ITL special, and uniquely suited for interstellar communication, is that the written script can be pronounced in three greatly different ways. The three ways to pronounce ITL are designed in a way to allow all the species of known space to speak in at least one of them. In theory, mastery of ITL requires the ability to understand all three form of pronounciation, which is one of the first things taught in language classes once learners have mastered the script, but even when people can only understand one of them they are still able to communicate through writing, as all three forms use the same letters.
Fluency in ITL is a requirement for almost all jobs in space and it’s the most common second language in most education systems, even before other local languages. In many frontier colonies with colonists from different countries of a planet, it has even replaced the traditional lingua franca of their homeworld, and for many spacers its the only language they know.
While all species are able to pronounce one of the forms of ILT, there is an uncountable range of various accents even within people of the same species. Some species have a harder time than others with understanding heavy accents, but in most cases it’s simply a matter of hearing the accent spoken for a few hours to fully understand it.
Not all species have a hearing range that can detect the full voice range of some other species. People traveling to systems where this is an issue for them when talking with the local population often wear hearing aids that shift their voices into a range they can hear. All personal communicators have the same feature and capture voice as it s spoken to play it back at a different frequency simultaneously. Better models are even able to amplify voices to the hearing range of other species and not just the species for which it was made. For visitors to other planets and stations, whose voice needs amplification to be fully audible to the locals, it is considered common curtesy to do so when possible, rather than to depend on them to fish out their own comms to understand what is beimg said to them.
The three forms of pronounciation are designed so that all species can pronounce one of them, though many are anatomically able to pronounce more than one. Talking to other species in the form they commonly can be an endearing party trick, but is almost never expected. Only one species has ever shown the ability to speak ITL in all three forms of pronounciation, but ironically they are the most isolationist species, that also uses very little verbal communication in general.
In addition to rules for faster than light travel, another thing that needs to be covered with specific rules is how communication is supposed to actually work. There’s plenty of people who lament how mobile phones make lots of investigation and mystery plots unworkable, and how such a simple and important technology absolutely has to be included in any new science fiction works. But after thinking about the practicalities in this area, I think it’s actually very plausible to have pretty limited communication in the way typically seen in older and more pulpy space adventures, even when you consider that the societies should have no barriers to create cell phones.
While my setting has Hyperspace travel to travel faster than light between star systems, I have decided that it doesn’t have faster than light communication. Ships in hyperspace are already treated as effectively blind, so why not also treat them as deaf?
The highly developed home systems all have very advanced and sophisticated local internets. On the homeworlds themselves, people have internet as we are used to. Outposts on other planets, moons, and asteroids in the system also have access to this net, but with severely limited bandwith and a time delay that can be on the scale of hours. People on these outposts can download text, audio, and even video at slow speed and reduced quality, but instant communication is limited to other people within the same outpost. For communicating with anyone else, they have to write emails, or record audio or video messages. Because these system-wide networks are separated from each other, they all are effectively their own environments with their own content.
To transfer information between system networks, the data has to be transmitted to a mail barge, which stores it on hard drives, then makes Hyperspace jumps to its intended destination, where it feeds the information into the local network. This takes several days, and storage space on these barges is limited and therefor comes with non-trivial costs. Mail barges are used to deliver written or recorded messages like mail, and files that have a long lasting relevance like books and movies. They also carry interstellar news between the big galactic news networks, but the local news of one system usually have little relevance for the people of other systems. The home sytsems have hundreds of mail barges going back and fort between them every day, but colonies might only see a single barge from their home system per day, and in many frontier worlds barges only arrive once per week or per month.
For characters to access one of these homeworld or colony networks, they have to fly there in their ships themselves, or send out a document request with a mail barge and wait for delivery with the next barge coming back, which can take weeks.
The homeworlds all have planet-wide mobile communication systems. These are good enough to gain signal access pretty much everywhere of the planet except for the poles on some less advanced worlds. Colonies are usually only the size of a single city or small country, and these have their local communication networks based on signal towers throughout the colony. The range of these usually only covers a couple of kilometers. Beyond that range, people won’t be getting any signals. Most worlds have compatible networks that allow visitors from other systems to connect to it by getting a short-term account for usually a week or a month on arrival when they go through customs or register their ships for docking. (It’s not that expensive and included in the docking fee when PCs arrive on a new planet.)
Smaller colonies and outposts don’t have even that and instead rely entirely on local wireless networks. Visitors usually only get access to these if they are staying with locals or rent a place to sleep. For communication outside the colony grounds, people have to use primitive but fully serviceable radio comunictors that are powerful enough to transmit signals over several kilometers. Most people traveling on space ships carry one of these with them all the time as they allow them to communicate with each other and their ship completely independent of local infrastructure within a limited range.
Most ships have communication systems to both log into local networks and communicate through radio with controllers on planets and other ships over distances in the millions of kilometers. But unless ships are really close to each other or in orbit around a planet there will be a considerable time delay.
Communication for Players
PCs can always communicate with each other through their radio comms within ranges of several kilometers and even their ship in orbit if it is right overhead.
On homeworlds and major colonies, PCs also have access to the local network within urban and developed areas.
There is no practical commuications between systems for PCs, with the exception of using the mail which will take days or weeks to get a reply.
When creating a new setting that departs from the normal conventions of reality, it’s always a good idea to define the new rules that are different. Of course, countless writers have always just made stuff up as they went, going with whatever seemed convenient at that point, but that’s just asking to run into contradictions and thing that just don’t make any sense later on. And these are pretty easily avoidable if you just take a bit of time to define the parameters by which the setting works at an early point of the process. In fantasy worlds, the major subjects are the magic system, the categories of supernatural beings, and the nature of other worlds where those beings come from. For settings set in space, I think the number one thing by a wide margin is the rules by which space travel works. This really was pretty much the first thing I was thinking about when I decided to work on this setting. It’s the one biggest change from normal life that really affects everything about economy, politics, and societies throughout the setting.
Something that always bothers me a lot in science fiction is that writers constantly use the latest new terms that have come out of physics to give their works an appearance of scientific backing and legitimacy, but then straight up doing things that have nothing to do with the concepts they are referencing. Personally, I feel highly certain that faster than light travel is physically impossible. Alcubierre drives are the one tiny sliver of hope that the true believers have, but that seems like a really long shot, and even if it might be theoretically possible, there are several complications that make possible applications much less convenient and practical than what you see in sci-fi. In order to not mangle any actual physics, I knew immediately that I want to go with the most purely make believe solution that doesn’t connect to reality at all: Hyperspace.
With Hyperspace, all the existing laws of physics remain completely untouched. It doesn’t violate reality by simply supposing that ships can, somehow, enter another dimension complete separate from our own, in which faster than light speeds are not just possible but easy. There is absolutely no evidence that such a dimension exists, but if there were, then all the problems with faster than light travel just magically disappear. So that’s what I am going for. In this setting, Hyperspace is a thing.
I think this is a pretty good example of Iceberg worldbuilding. Pretty much everything in this post is meant to be stuff that remains under the water. Players don’t need to understand or know any of this to play a campaign. The purpose of this whole system is to be able to answer questions if players ask about how these things work, and to avoid situations where players realize that two things that have been established through the course of the campaign make no sense and contradict each other. Players don’t need any of this to play adventures, but I need to understand this to set up adventures that will hold up to scrutiny.
The Nature of Hyperspace
Hyperspace is a separate dimension from normal space that has very different laws and properties. It takes very little energy to cover incredible distances many times faster than the speed of light, and the engines required to enter and exit hyperspace are simple enough to be very widespread and accessible. In this setting, Hyperspace jump capable space ships are as common as planes and similarly expensive to operate.
Every point in normal space has a corresponding point in Hyperspace. To move between any two places in normal space faster than the speed of light, a ship simply jumps into Hyperspace, flies to the point that corresponds to its destination, and then jumps back out of Hyperspace again. However, things get greatly complicated by the fact that Hyperspace is extremely warped and twisted. In real physics term, the geometry of normal spacetime is flat, but the geometry of Hyperspace is very much not, and there are no indication of any repeating patterns in the curvature of Hyperspace. This means that even when you know the exact position of two or more stars in normal space, you have no way to tell the positions of their corresponding points in Hyperspace. And even if you have the Hyperspace coordinates of two stars, you can’t just draw a straight line between them to know how to get from one star to the other. Even knowing how to get from star A to star B, and from star B to star C, does not really tell you anything useful about getting from star C to star A.
Determining the corresponding points of stars in Hyperspace and the paths to move between them is part of the field of astrometry. And while moving a ship through Hyperspace is really quite uncomplicated in practice, finding the Hyperspace routes that connect stars is extremely difficult and requires the expense of huge resources. Since the warping of Hyperspace is effectively random, every route between any two stars has to be measured and calculated separately. Accordingly, most star system in the core of known space have only two or three known routes leading to and from them, and many frontier systems are dead ends as Hyperspace travel is concerned. The only place to go from them is back to the system from which you came. In practice it is much cheaper to simply make multiple Hyperspace jumps between systems to get to the one that is your destination than trying to calculate direct routes between all the possible stars people might want to get to. Accordingly, Hyperspace charts look like subway train system maps with many stations that the routes are just passing through, and several stations where two lines cross and you can switch from one line to another.
Since calculating Hyperspace routes takes a long time and is expensive, astrometric services pick new systems to connect to the network not at random. Instead they rely on data from astronomic observations of newly discovered planets around unexplored stars. (Something scientists have learned how to do in the last 20 year, and as such you don’t see in older science-fiction.) There are many exploration companies that commission routes to be calculated to systems which they think have great potential for exploration. But often astrometric services just take a gamble calculating new routes to previously unexplored systems and hoping to make their investment back with sales of licenses for the new routes. But more often than not, these new routes turn out to lead to systems that don’t have anything anyone is interested in, and as such these routes simply expire after 10 years without getting any new updates.
A further complication is that all objects in space are always in motion. Stars move around their galaxies at very considerable speeds and even the galaxies themselves are constantly moving around in space themselves. This means that the Hyperspace coordinates for any stars are constantly changing. In theory, you could calculate a route for a Hyperspace jump between two stars at a single moment in time, but even just seconds after that calculated moment the route would leave you somewhere in empty interstellar space with no way to find your way back to a known system. Since this isn’t any useful for almost all space travel, a single Hyperspace route is actually a big catalog of data that lists the correct path for travel between two stars for any moment throughout a longer time span. For smaller routes, this time span is usually 10 years, while for the routes in the home systems it is 100 years. Nobody would go and explore a new system or set up a mine or colony if that system might become unreachable in a few weeks or month, after the route expires and nobody bothered to have an update commissioned. The government owned astrometric services of the home systems are constantly releasing new updated catalogs for the main trade routes, each time extending the expiration date back to 100 years. But in small frontier systems, things can get quite tense if the last updates are reaching their expiration and there is no news of new updates being announced. Often small colonies have to commission a new route update to connect their system to the rest of known space with their own money, which can be a huge financial burden. Colonies that can’t afford the huge costs often have to be abandoned, but there are countless stories of stubborn colonists who supposedly held out and accepted being cut of from the rest of the galaxy forever.
Starship owners have to buy expensive licenses from the astrometric services to get access to their catalogs of Hyperspace charts, which is a substantial part of the cost of space travel. Of course, there are countless unlicensed charts making their rounds on the black markets of the frontier. But since a ship that gets lost in interstellar space for all eternity can’t come back to complain, the accuracy of these black market charts is always extremely dubious. Few captains are desperate enough to gamble their lives on these.
While ships in Hyperspace are effectively blind and have no way to tell where they are going, the gravity of massive objects in normal space still has effects on Hyperspace and cause it to warp even more than usual. Accordingly, the routes of Hyperspace charts really only show how to get to the general vicinity of a star. Making a ship arrive at a specific point inside a star system is for all intents and purposes impossible. While stars themselves are actually really small compared to the scale of a system, the warping of Hyperspace near them becomes stronger the closer you get, which makes it actually pretty easy to accidentally get much closer than expected or even come out inside the star itself. Usually navigators keep things safe and jump out of Hyperspace somewhere in the outer part of the star system where the risk of randomly appearing inside a planet are negligible. Similarly, jumping into hyperspace too close to a star could lead to navigational errors that lead to a ship getting lost in interstellar space.
In practice, this means that between arriving at or leaving from a planet, and jumping in or out of hyperspace, ships have to travel considerable distances at sublight speed. While the Hyperspace jumps themselves often take only a few hours, flying between planets and jump points can take from many hours to several days. Small stars with low masses have much weaker gravity and all their planets close to them, so transit times in such systems are on the low end, while large stars with great masses have very strong gravity and their habitable planets much further out, resulting in the very long transit times.
Another quirk of the warping of Hyperspace is that even with the best navigation computers, both the exact point at which a ship jumps out of Hyperspace in another system and also the precise time at which it arrives are somewhat random. Fleets leaving a system together always arrive at their destination scattered over great areas and arriving over the span of several minutes and sometimes even hours. Fleets always require several hours to regroup after a jump, followed by several hours of transit time to reach the planet they are headed for. This leaves people on the planets many hours to notice them and prepare for their arrival, which makes surprise attacks with space ships impossible.
Hyperspace jumps require fuel. Licenses for Hyperspace charts are included in the regular upkeep and maintenance costs for spaceships, but fuel for the Hyperspace engines is a resource that has to be tracked at all time. Players making journeys to other systems have to check if their fuel will last them to make the journey and return trip, or plan to make stop at fuel depots along the way. I think fuel stops can be a great way to introduce randomized encounters into the campaign. Aside from the PCs running into interesting people during these fuel stops and getting into trouble while waiting for their ship to be ready to continue their journey, you could also have various complications like the fuel station turning out to be inoperable, causing long delays, or being destroyed, causing potentially serious problems with keeping the engines running. Fuel costs also seem like a great way to put financial pressure on the players. Without fuel they get stuck and so are forced to make money, or can’t afford to be charitable to people who would really benefit from their cargo. Or they might be driven to try to steal fuel somewhere. I think there’s great potential in this that could lead to wonderful organically developing side adventures.
Hyperspace Travel for Players
Even with all the theoretical background stuff, the things that players need to understand is really simple:
Ships can only go to star systems that are on the map. And every journey has to be taken along the marked lines. Every jump requires a unit of fuel. (Or two or three units, depending on the size of their ship.) After leaving a planet, they need to survive for a couple of hours before they can make the jump. Even if pursuers decide to follow them through Hyperspace, they will arrive far enough apart on the other side to reach a planet before the pursuers catch up to them, and if they manage to make another jump before the pursuers arrive they will have lost them for good.
That’s really all the players need to know. Anything else is just for curious players that enjoy these things, but I find it important as the foundation that explains why these few player facing rules are the way they are and to make them consistent even at closer observation.
I’ve been working on this fantasy setting stuff for many years now and it’s a huge ongoing project that I don’t think will ever reach a point of being called “complete”. Once or twice a year I feel like taking a break from it for a while, and often I’ve turned to tinkering with ideas for a Star Wars campaign. But last week I was playing Kenshi while simultanepusly having Dune on my mind and an urge to put on the Cyberpunk 2077 music again, and I was overcome with the sudden drive to create a majestic Space Opera setting myself. Something that feels like watching an old monumental movie with grand landscape shots in ultra-widescreen cinemascope. Something with the imposing style of 1920s architecture and blend of dusty grime and lavish decadence.
I am still a giant Star Wars fan; as big as you can be before it becomes cringy. But I think the modern iterations of the last 20 years have lost most of the original charm, and I am growing a bit cold on the old Empire and Rebels thing, which never has really been what I thought as compelling game material. And I am also not feeling like Jedi right now. Smugglers is always an option, but for such a campaign you have to create a lot of your own new content, and in that case I am feeling like doing my own original thing from scratch right now. Probably just as a fun exercise, but maybe there might be a campaign coming out of this at some point.
My main reference is of course the greatest movie of all time. The Empire Strikes Back. Specifically I am thinking of Bespin and Lando, but also the bounty hunters. Dagobah also has a stunning feel that I don’t mind refering to for wilderness environments either.
A Princess of Mars. The Granddaddy of them all. This is where most of the other sources on my list get their main influences from. Swordfights, radium guns, desert palaces, space princesses, alien monsters. Barsoom has it all. And I am really quite fond of the aesthetic of Antiquity most artists always associate with it.
Dune. Admittedly mostly the aesthetics of the 80s movie and a bit of the mystic elements, but technologically and socially my setting will probably be very different.
Shadows of the Empire. Star Wars again. I think this one was the last hoorah of classic Star Wars, happening around the same time as the Special Edition relreleases and testing if the market was there for a Star Wars relaunch. I am the first to admit the Shadows of the Empire is not particularly good as a story, and I only played the game and read the book, but not the comics. But this story hits the right notes for me to slighly blend the classic Space Adventure style with Noir elements. Not sure where that came from, but even as a 13 year old or something like that, I always imagined the sections on Corruscant as looking like Noir movies with towering 20s architecture.
The Knights of the Old Republic comic series, which takes place at a similar time and some of the same places as the game but is otherwise a completely separate story. It stands out to me among Star Wars stories in that it’s not about the typical big damn heroes, but rather follows a simewhat obscure B-Team that has its own adventures that mostly happen alongside the big galactic events but occasionally have short, important impacts on the greater picture. What I love about it is that the characters are not the big invincible heroes and their goals seem more personal, even when they are interacting with the great poweful leaders of their time. I find that a much better reference for more pulpy space adventures than the big epic adventures of the main cast, which are also much more practical for playing actual games.
Mass Effect 2. While in many aspects more military hard sci-fi, the series is still well at home among the space operas, and especially so in the second game that has more stories set in the underworld and doesn’t deal with intergalactic politics like the other two games. There are some just gorgeous environments that I happily salavage for descriptions, but in particularly I love the way the series creates its alien species. There is only a dozen or so in total, and with two embarassing exceptions, they all have their own thought out cultures that don’t make any of them a generic villain species. I think the cultures of Mass Effect are one of the geeatest achivements in woldbuilding ever done, and it’s a model I fully embrace for my own species. And of course Lair of the Shadowbroker is an amazing pulpy noir adventure.
Blade Runner has a fantastic environmental design which I am totally going to straight up copy for at least one planet, though the story and technology have nothing to do with what I am planning.
And in the opposite way, Cyberpunk 2077 is a game that has a lot of thematic a d narrative elements I want to make use of, while the visual style is really little overlap with the imagery I want to evoke.
The Hyperspace Opera is set in a corner of its own galaxy, completely unrelated to the real world. It’s a pulpy Space Adventure setting with swashbuckling snd gunslinging, a style in which realism doesn’t really apply on the list of priorities. Though as an astronomy nerd who knows a bit or two about chemistry and demographics, my wish is to avoid things that are totally unrealistic when a much more plausible alternative will still make for an equally exciting and interesting setting.
The setting will have a dozen or so space traveling species, and since unlike most classic science-fiction authors I have learned about “demographic transition” back in seventh grade, their populations are each around 10 billion people or so. Which is around the scale at which the human population of Earth will peak out in the middle of the century before stabilizing or possibly even decline. And that is for all the members of the species on both the homeworlds and all their colonies. People aren’t suddenly starting to have more children because they moved to another planet. In total, I think there will be only 300 or so inhabited planets in the entire known space, most of which have only tiny populations of a few thousand people. And only 30 of these will be part of the local region that gets actually developed for play.
Because of the way stars and planets form, no natural resources are anything remotely qualifying as rare. Anything that you might want from a planet is just as abundantly available on dozens of other planets. With only a few hundred inhabited planets, this makes fighting over patches of dirt pointless. You can always find another source if one you found is already claimed, and it’s much easier and cheaper than tryimg to fight someone for their claim. There is no scarciry of natural resources in the setting. The value comes from the work to extract and refine them.
Hypsrspace travel in the setting is pretty easy and quite cheap. With there being an endless abundance of planets of every imaginable shape, it’s very easy for people who don’t like the way things are run around where they live to just pack up their things and leave for one of the many frontier colonies or start their own. With blackjack and hookers!
In a setting with no scarcity of resources, unlimited space, and easy interstellar travel, there is no source for conflicts over territory. Interstellar wars between governments are extremely unusual and their space fleets are really much more like police services or coast guards than military forces. The dominating source of violence is crime, which can come in many different shapes or forms.
The main areas of conflicts are out in the remote frontier colonies. The home systems of the various species are all quite safe, which means there is little adventure to be found. But out on the frontier, there are no meaningful governments or powerful security forces, and things are very different.
While the lure to settle in a colony on the frontier is very enticing to many people, very few of them are imagining a life of scraping in the dirt to grow their own food with muscle power alone. They still want all the comforts and conveniences of the homeworlds and major colony worlds, but being much too small for the industries to produce advanced technologies themselves, they rely on imported machines and goods. And usually the only things to trade for them are whatever natural resources can be dug out from the ground with the simple machines the colonists brought with them on their first arrival.
This is where the great companies of the industrial barons come into the picture. These companies sell about anything that people could want, both in the home systems and most remote colonies, amd they are always in the market for valuable ores of any kind, especially when they can avoid the trouble of digging them up themselves. But as perfect as this arrangement seems, without powerful governments out in the frontier, it’s all a giant setup for massive exploitation. It is open knowledge that the great oligarchs are organized in far reaching cartels to make sure nobody pays the frontier colonists more than a pittance for their ores and agree to not undercut each other with the outrageous prices they demand for the goods they export to the colonies. Everything is set up exactly to squeeze as much money as possible out of the colonies and leave them just enough to keep them from collapsing completely and lose these sources of cheap ore and well paying steady customers. The companies also pull such tricks as not selling any machine parts with the longer service lives that are available in the home systems, or engineer crops that can grow in poor alien soils but don’t produce seeds on their own requiring the purchase of new seeds every season.
The home systems are big and important enough customers so that the governments can enforce regulations and dictate terms, but the frontier colonies have no other suppliers to turn to, and the companies are more than willing to let a few colonies collapse just to send a message to the others what happens if they refuse to do business at the oligarchs’ terms. Some colonies have found ways to escape the clutches of the companies and unite together to pool their resources for better bargaining positions and form industrial cooperatives that build shared factories for advanced technologies that would not be economically viable for a single colony. Any such attempts to unite and collectivize are a thorn in the companies’ sides and a threat to the oligarchs’ power if they are allowed to succeed. And without strong and powerful governments, there is little that js stopping them from using every single dirty trick there is to sabotage them.
Yes, you got that right. Somehow this attempt to create a space opera setting inspired by 1920s architecture and design turned very quickly into a setting about the evils and struggles of industrialization. I was already pretty far into the process when I noticed this, and I think it’s actually really cool. That’s a great theme for pulpy science fiction that I’ve never seen done before, and which I think can be an amazing source for many kinds of conflicts.
A setting like this could easily be very one-dimensional and preachy by making it all about how awful industrialists are and how collectivization is the answer to all problems of the world. Done a thousand times with no real room for any interesting nuances. But being whatever the opposite of a tankie is, I think there are much more interesting stories to interact with in the divisions of the labor movement and the devastating flaws in anti-capitalist ideologies. While much good has come out of the labor movement, communism has not just been a complete failure, but a horrifying disaster of unprecedented scale. Of course you can always have industrial saboteurs and company security looking to break some knees as wonderfully evil antagonists and villainous burocrats, as they should be. But it’s also easy to imagine corrupt colonial leaders who take oligarch money or preferential terms for their own colony in turn for obstructing their neighbours attempts to unite. And of course idealistic small settlements beyond the reach of any governments are te perfect spawning grounds for countless wouldbe tyrants. And space pirates. Always got to have some space pirates.
But with all of that said, what are players supposed to do in an actual game that is supposed to be played? What I have in mind is a classic staple of this kind of space adventurs. The humble independwnt logistics entrepeneur. The space trucker. And or smuggler. The campaign structure I have in mind is about a small cargo crew making occasional deliveries of small shipments to frontier settlements. Out there they quickly become aware of the exploitation going on and the plight of the colonists, as well as the widespread coruption and violence by press gangs and company security. As owners of a small freighter that are no strangers to the concepts of smuggling, this is an environment in which huge profits could be made. But also one in which the players might find it in themselves to offer support to the struggling colonists. But even the most charitable hearts still need to eat, and keeping the lights running on a freighter isn’t cheap. At the end of the day, the campaign is supposed to be fun and exciting pulpy space adventurs. All these ideas for social and economic struggles are really there to provide an environment that creates opportunity for all these things. I think generally the motivations of the actors in this environment are fairly simple to grasp, but they are different from what you usually get in fiction in general and in RPGs in particular.
To close this up, some additional small details:
Artificial gravity exists, because it always does in Space Opera. But there is no explanation given for this marvel that defies any known principles of physics.
Firearms and ship cannons come in the form of railguns. They are not lasers and work just like normal guns. Except more spacey. They also feel right as big chunky things with a somewhat primitive aesthetic rather than sleek and shiny.
Swords and knives are cool and awesome. Knives are actually extremely deadly in a gunfight at short distances,and fights on ships tend to be extremely close. They are also useful when you have to make sure to not shot anything important, and unlike railgun power cells, they are not picked up by most detectors. It makes sense for lots of people to have blades and to know how to use them.
There are no starfighters. They don’t really make sense when you think about how yoh could fight in space, and once I started thinking about how a setting without them could look like, I think you can actually have something really cool with only full sized ships.
No psychic powers. I might change my mind if I find a really good reason, but currently I just don’t see them needed for the stories and situations I have in mind.
No robots? They are of course an old classic element, but currently I don’t really see how theh would meaningfully contribute to the setting with their existence.
No cybernetics or transhuman nonsense. They are all the rage in recent years, but I think they feel out of place with otherwise 1920s retro-aesthetics.
There is no galactic empire. Because the ways I plan space travel and communication to work, governments rarely control more than a single star system, though there are many small comfederations consisting of a home system and a dozen or so autonomous major colony worlds.
Business oligarchs are the space aristocracy. They don’t usually use noble titles (sorry Star Wars), but they are an aristocratic merchant caste in all ways that matter.
No evil species. As I mentioned earlier on, I really like having aliens as actual people instead of bland stereotypes as a convenience for lazy character writing.
Lots of exotic planetary environments. RPGs are not limited by effects budgets, so we can have all kinds of different suns and moons and other fun things to make planets distinguishable and evokative.