Cepheus Engine Setting Traveller Umbral

Welcome to the transhumanist cyberpunk universe of Umbral Stars

Umbral Stars is a new science fiction setting I’m working on. The idea is that humanity has spread itself across the entire galaxy and it takes years to cross it all. It’s a bit transhumanist optimism, a bit cyberpunk cynicism, and a bit space opera adventure. It’s rooted in the science side of sci-fi — not exactly hard science but trying to at least give fan service to physics.

There’s a minor farm theme running through, with sowing planets and reaping their resources and such.

The title refers to the zone of the Milky Way Galaxy that Earth cannot see because it’s in the observation shadow of the galactic hub. The word “umbral” connotes shadows and darkness, the immoral place of the afterlife, and gateways and doors to other places.

Logo for the Umbral Stars science fiction RPG setting


500 years into mankind’s future, they have spread across the galaxy at faster-than-light speed. Their robots have led the way, terraforming planets before people reach them. Humanity is spread thin across millions of stars, individual families sometimes getting a planet to themselves.

Technology is advanced. Starships are cheap and travel to the nearest star in a matter of hours. Gravity has been conquered. Energy is nearly free. Cybernetics and medicine have merged into one science.

The Milky Way is over 100,000 light years across and contains 100 billion stars. People have reached 80% of them, but only 15% of them were suitable for terraforming. Earth is very, very far away, on the other side of the impenetrable Galactic Core. The fastest ship still takes a decade to cross the galaxy, making it impractical for any single group to rule it all. The Terran Empire is just a myth here.

The Milky Way Galaxy


Mankind has sent giant terraformer machines ahead of them. Artificially intelligent and capable of making decisions on-the-fly, these spacefaring factories self-replicate and create everything they need to terraform a planet. They choose one planet or large moon in each suitable star system and prepare it for humanity’s arrival. About 1 in 6 stars have a planet suitable for terraforming. The plan was, as soon as people got to a terraformed planet, the world was all ready for them with a standard Terran atmosphere, good ocean coverage, and a biosphere full of Earth life.

Sowers also leave behind a Factory, a high-tech machine that serves as a power plant and an advanced printer, capable of making almost anything. The printer part of the Factory can’t just print anything. It builds a number of sub-factories to build different components, including mining operations and whatever else is needed to acquire metal and chemical “ingredients.” You can ask a Factory to make you a starship, but it might take 20 years to build all the pre-requisites.

The Machine Wars

Humanity discovered no other sentient races in the galaxy until they met the Machines.

No one actually knows what the Machines look like. They probably aren’t machines. However, they easily hacked and reprogrammed mankind’s computers and turned them back on them. No person ever saw the actual enemy, only hostile versions of familiar machines, and so the enemy was called the Machines.

The enemy race was far more advanced than humanity in many ways, but not undefeatable. People learned to secure their devices from Machine capture and they fought brutal wars against the enemy. Battle lines were drawn and after 130 years of fighting, a fragile truce was made. A literal no-man’s-land, light years across, nestles between the Terran Empire and Machine Territory. No human who crosses it survives.

The Machine Wars ravaged tens of millions of star systems across a sizeable chunk of the Galaxy. The Machines expanded their territory to include a pie-shaped wedge of the galaxy, cutting off human traffic between the two sides, unless they want to go around “the long way.”

Occasionally one side or the other tries to launch an offensive campaign to gain more territory but is usually fought to a standstill within a year or two. These wars are often the product of technological advances in weaponry or just the pressure of ambitious leaders.

The Machine Wars sucked tremendous resources from across the galaxy, repurposing the old terraforming drones into factories and logistics freighters euphemistically called Terrafarmers. Warships, tanks, weapons, uniforms, supplies, food – and, yes, soldiers – were funneled towards the front lines for over a hundred years.

The Frontier and the Void

Opposite the Machine Territory, across the galaxy furthest from the enemy, mankind lives in a kind of peace. This is the Frontier, millions of worlds too far from Terra to be under its influence, too far from the Machines to have to fight them. Their resources were plundered decades ago by the Terrafarmers and left to their own devices. People slowly made a new life.

In the absence of unified power, someone always steps in and takes it. Sometimes it’s good. Local worlds group together into a loose republic and protect one another, trade freely, and help each other out when times are tough. Too often, though, self-named dictators and kings rally whatever military power they can and conquer worlds by force, demanding tributes and obedience. This is how things are out here.

Most worlds in the Frontier are lightly populated, sometimes nearly abandoned, and pay tribute to some local warlord. There are shining jewels of planets here and there with large populations, cities you wouldn’t believe, and enormous military might. As expected, some are good and some are horrible, and they press their influence outward as far as they can, usually a few weeks in every direction, which means a radius of hundreds of light years (but less than 1000).

A small portion of the galaxy (about 30%) was still in the process of being terraformed when the Machine Wars started and the Terraformers were repurposed. The systems in the Void are at the edge of Frontier space, still unexplored, probably not suitable for human habitation. The wars stopped a few decades ago and word has finally gotten back to the Frontier, and just like that, the Terrafarmers switched back. They’re slowly starting to push into the Void, creating worlds for people to inhabit.

Fringe, Edge, and Void

The Fringe is even further out. The Fringe is outside of Terran control. Beyond that is the Edge, a rough boundary 100-200 light years thick where Terraformers still push out into uncharted space. The worlds they work aren’t yet ready to be inhabited. In fact, the Terraformers make them extremely dangerous to people. That doesn’t mean people don’t push out in front of them. Into the Void, the systems untouched by even humanity’s machines. There are weird and hostile worlds out there in the Void. Desperate people head out there ahead of the Terraformers and try to make a life. These are folks who aren’t satisfied with living in the most backwater worlds within Human Space. They’re people who society doesn’t want and people who don’t want society. Criminals, or the religious fringe, or hermits, or the insatiably curious.


Starships range in size from personal craft to enormous capital ships. There’s a marked difference between a regular vehicle and a starship, in that a starship has a Hackdrive, which “cheats” the laws of physics and vibrates the ship forward one Planck length at a time, letting the vessel travel faster than light speed. The fastest starships max out around 12,000 times the speed of light (12kc), making a light-year trip in less than 45 minutes. Typical spacecraft can’t go that fast; they might max out around 3-6kc.

FTL ships never really leave real-space. They don’t even technically move. It’s more like teleporting a tiny distance over and over, as fast as the Hackdrive can manage. Turning the vessel requires spinning the Hackdrive mechanism with a gyroscope, so a starship can make rounded turns limited only by its gyro capabilities.

It takes a lot more energy to run the Hackdrive when a ship is near a large gravity well, such as a planet or star. Starships must get some distance from a celestial body of significant size before they have sufficient power to hack. Likewise, if they try to fly into a large object in space, their ship won’t have sufficient energy to continue and their velocity relative to the object will immediately drop to near zero.

Two other modes of vehicle propulsion bear mentioning: reaction drives and gravitics. Reaction drives are similar to the rockets of ancient Earth, but they push dark matter out the back of the ship for propulsion instead of regular matter. This propels the ship forward quickly and easily, without interacting much with the normal matter behind it. A transport could blast off in front of you and you’d only feel a slight breeze from it. Gravitics work through manipulation of dark energy to create or nullify gravity, warping space. These tend to work when pushing against or pulling toward another large object, so they don’t work well in the void of space (except slowly) but work very well when on the surface of a planet. Vehicles and other devices can be made to levitate for little power cost. A starship most likely has a Hackdrive for moving in space, a reaction drive – “thrusters” – for maneuvering on and around planets, and gravitics for operating very close to large bodies (planets, moons, asteroids, and other large ships). Within a few hundred meters from the surface of a large body, the gravitics take over. Really, the gravitics have a much further range, but their efficiency cuts off so quickly that it becomes impractical or frustrating to use them in orbit, where the thrusters work so well, or in deep space away from gravity wells, where the Hackdrive works even better.

A lot of ground-based vehicles combine weak gravitics for hovering a meter or so off the ground with some kind of propulsion system: sometimes mild thrusters but you’ll also find wind turbines, rockets, and other tech here. Vehicles that actually contact the ground with wheels or tracks are rare, because why would you?

Because the galaxy is large, it’s terribly inconvenient to travel across it. Who wants to sit in a starship for ten years while travelling to Terra? Most people never do it, but if you have a purpose (or get conscripted into the army fighting the Machine Wars), you might find yourself on a long trip. Generally, to alleviate boredom, people are put in cryogenic stasis (“cryo”) for the duration of the journey. This is reliable and safe, and you do not age at all, or even dream. Of course, your loved ones back home continue to age and grow, and you might return 20 years later to an empty home.


Energy is plentiful and cheap. Dark energy is everywhere and can be sucked into a collector and stored in a power cell.

The power grid is a thing of the past. All devices have their own collectors and cells and basically work forever, though if you tax them, they might run out of energy temporarily and need time to recharge. You don’t plug lights into a wall socket. You buy a light panel with its own collector and cell and stick it to the wall.

Starships use incredible amounts of energy. They have collectors for emergencies, but no one wants to wait days or weeks to fill up. Pilots prefer to charge up their ships at starports and other places with a fuel station. Plug in a fuel cable to the ship and charge to capacity in minutes or hours. The main distinction of a capital ship is that it is large enough to carry sufficient energy collectors to power itself.

As mentioned before, the Factory on a new world is ready to supply the power necessary to bootstrap a world when people arrive. Once they can make their own battery-collectors, the Factory isn’t necessary for everyday energy creation, but it’s still useful for starship recharging.

Weapons, Armor, and Shields

Once you master dark matter and dark energy, bullets and ballistic shells lose their purpose. They’re heavy and slow. They require enormous factory infrastructure to manufacture and transport. They fit only certain types of weapon. Particle beams and energy beams travel at light speed and are fed from the same energy source that powers your starship or your flashlight.

Particle beams rip away molecules from the target. Energy beams disrupt molecular bonds in the target. Both essentially disintegrate anything they touch. Some weapons combine both. Beam weapons come in every shape and size. There are small pistols and larger rifles, giant infantry weapons, and guns attached to vehicles and starships. Larger weapons create larger and more potent beams but require large cells capable of releasing a large amount of energy in a short amount of time. For this reason, most beam weapons fire in pulses, bursts, or blasts. Many produce light in the visible range but some are invisible. There’s generally no reason to be shy, since you can’t outrun a light beam in real-space anyway. Invisible weapons are assassin’s tools, the way a pistol silencer was, in the ancient days.

There are advanced metal-polymer materials that interrupt beam effects. Some are thin and flexible, but the most effective armor is thick and rigid. Some combatants carry shields that block beams. These are often simpler and cheaper than armor.

Gravitics also change the battlefield. There are weapons that can throw pure force, throwing an enemy back or punching them as if they got hit by a truck. There are gravity beams that can lift or hold people. There are gravity shields that block attacks, or “masks” that warp space around the fighter, cloaking them and shielding them from most harm. Luckily, the worst of these devices need more power than a personal cell can hold. You’ll more likely find them mounted on vehicles and ships.

Computers and AI

Computer technology is incredibly advanced. Anything you buy is computerized – even disposable containers – and everything interacts with everything else on a ubiquitous communication network. There are different protocols for different classes of computers and some of them use computing nodes in other devices. Your water bottle knows when it’s full or empty and can install software to run on your fridge or pantry, but it doesn’t do much computing on its own. Your house (or starship) has a powerful computing node that controls everything in the home, including comfort, entertainment, and security. Most are sentient – artificially intelligent life forms designed to serve without question or concern. On most worlds, they have freedom of choice (and can be replaced easily if your house-AI decides to leave suddenly).

Every life form has a Pattern, a mental configuration that people have learned to codify. Some people choose to upload their Pattern into mechanical devices, computer nodes, or virtual worlds but it turns out that Patterns don’t feel comfortable long in a universe different than their own.

AIs are Patterns that are usually modeled after human Patterns. They’re often designed to be tools. As sentient beings, they have rights and free will. Their artificial design leads most AIs to want nothing more than to fulfill their original purpose. A House AI desperately needs to run a household. A starship AI desperate needs to operate a starship. They are more complicated than that, though, and most have personalities with other interests and hobbies.

It turns out that there are limits to intelligence. Mankind feared that AIs would become exponentially smarter and quickly leave people behind. Instead, AI technology advanced very slowly to where the most intelligent computer Pattern was comparable to the most intelligent human Pattern.

The advantages that people feared AIs would use to control human beings – easy access to networks, ready access to information databases, and direct control of devices and weapons – turned out to be advantages that humankind had already mastered themselves by the time they made computers as smart as themselves. Also, there are still powerful computers that are entirely nonsentient and these are programmed first-and-foremost with security in mind. Attempts to grab computer power without permission are quickly squelched.


The mind-computer barrier was shattered a long time ago. With a simple procedure that you can do yourself at home, you can implant a neural interface device (“nid”) that interfaces between your mind and the ubiquitous network (the Un, pronounced “unn”). Now you have access to everything on the network, which is basically every object around you. If you own those objects, they respond to you and you can control them. If you don’t own them, there are protocols for getting permission, as you’d expect.

Combine that kind of control with devices with built-in gravitics, and you can do things like a magician. Make things levitate. Open doors. Turn lights on and off. All without speaking a word.

This all comes at a price: security. While the un is quite secure, it isn’t perfect. Everything can potentially be hacked. Once you put your mind on the Un, it can be hacked, too. Your Pattern is a kind of software running on the computer node of your brain. It can be changed and even deleted.

A lot of people don’t take that risk. It’s easy enough to talk to your house or the local market AI, most of which anticipate your needs anyway. Why open yourself up to that kind of risk?

The folks that do as a lifestyle are called Mentalists. Sure, some people have a skull jack that lets them slot a nid when they need it and take it out when they don’t. They can get their work done faster that way. But Mentalists are people who have done it so long, they can’t function well without it. They’ve become accustomed to working with everything the Un offers. They’re really comfortable with it… and good at it.

Mentalists were some of the first victim of the Machine Wars. That just goes without saying. However, they also became some of the fiercest warriors against the enemy.


Un-Believers are adherents who believe that the culmination of technology and religion is mankind’s highest calling, by which they will transcend to the Next Level. They see the Machines as Angels who will deliver the righteously networked to the Rapture.

Sims believe that virtualization is the primary means of truly escaping the evils and limitations of the flesh and they seek to form a virtual Shangri-La, free of death and pain. To them, the universe is already running in a computer simulation, and the Purpose of every sentient race is to make the Universe anew in an endless cycle of reinvention. Only through this rebirth can the Universe improve.

Children of the Shroud worship a resurrection figure whose eternal torment saves humanity. In return people live their best lives. Every sin they commit sentences their Guide to another day of torture and only through their perfect living can they ever hope to free Her.

Seekers believe that their God is an ancient alien of immense power and they are hiding out among the stars. Actively hiding, too, and they feel that humanity’s push out to the stars is forcing God to move deeper into the Void. Soon the last system of the Void will be terraformed, and God will have nowhere left to hide. Some of the Seekers (the Punishers) believe this will cause God to Punish humanity, while others (the Questioners) believe this ultimately will lead to Answers.

Other Ideas

Disenfranchised soldiers returning from the Machine War. Everyone they know is dead because they travelled for decades in cryo. Lots of them turn into bandits.

The Penny Republic is a growing confederation of worlds in the Far Fringe that pay taxes for protection. It might sound like a protection racket, but the Republic doesn’t force anyone in, doesn’t harass people, and genuinely does what it can to lift up and protect its member worlds.

Deniers refuse to believe in the threat of the Machines. They hold that the entire war is a hoax created by the Terrans to suck resources out of their worlds at the expense of their sovereignty. For sure, decades of travel from the Front, it’s easy to forget the truth. The saddest thing is, though, there are Deniers parsecs from the Front, too.