Let's Read “Traveller: Core Rulebook - World and Universe Creation”

Procedures Make the World Go Round

In the previous chapter, we read about Traveller's Trade system.

In a Science Fiction game with Faster than Light (FtL 🔍) travel, Referees may want some resources for making their universe. You could easily use Traveller Map for your campaign. Personally, I have found that I better hold in memory the worlds that I either make. This is likely more related to the process of taking notes; In my day job, I have a better understanding of the code I write than the code other people write.

In the World and Universe Creation chapter, we’re going to go through three main concepts:

Sectors and Subsectors
The map and organization of systems throughout the galaxy
Star Mapping
The process for randomly populating the star systems of a sector or sub sector
World Creation
The process for randomly sketching out some defining world characteristics

Sectors and Subsectors

The Sectors and Subsectors section frames some conventions in Traveller. A sub-sector is an 8 parsec by 10 parsec region; The sub-sector uses hexagonal grid and conveniently fits on an 8.5 inch by 11 inch sheet of United States (USA 🔍) Letter paper. Each cell on the grid representes a 1 parsec by 1 parsec region.

A sector is a set of four-by-four sub-sectors. These conventions ease note-taking and information organization.

Directions in space really need to be relative; And Travller provides that.

North, south, east, and west are insufficient terms for referring to directions within the galaxy. Instead, the following conventions have achieved widespread acceptance when referring to direction: Coreward – toward the galactic core; Rimward – toward the rim of the galaxy; Spinward – towards the direction the galaxy is rotating (or spinning); Trailing – opposite the spin of the galaxy.

Star Mapping

With an 8 by 10 hexagonal grid in hand, we start checking each hex for a “world” (and an attendent star or stars).

By default, each hex has a 50% chance of having a world. There are recommendations for adjusting probability based on its (e.g. -2 in a rift sector, -1 for sparse, or +1 for densely populated sectors).

Systems may have starports and bases; More on that in World Creation.

Each system may have one or morse gas giants; On 2d6, rolling a 9 or less indicates the presence of a gas giant. These are useful for skimming fuel.

Systems may have travel advisories. Amber means caution and Red means danger, perhaps even interdiction. We’ll get into that further.

Also on the sub-sector map consider the communcation routes and trade routes.

Communication routes are a bit of a Referee fiat; They do represent the flow of information through the sub-sector.

Trade routes link worlds, we get a bit of guidance on how to connect worlds based on supply and demand:

An Industrial or High Tech world within 2 parsecs of an Asteroid, Desert, Ice-Capped, or Non-Industrial world will have a trade route.

A trade route will content any High Population or Rich world within 2 parsecs of an Agricultural, Garden, or Water World.

World Creation

Traveller provides procedures for rolling up several a planet’s attributes. These provide some guidance on what to perhaps expect when jumping into a system. Though it’s possible the information is out of date.

During world creation, you roll up the following attributes:

The diameter of the world
The type of atmosphere
The prevelance of water
The world's population
The type of government
Law Level
The stringency of law
The quality of the start port
Tech Level
The average technology presence on the world
The bases, if any, for this world

These attributes create the Universal Planet Profile ( Universal Planet Profile (UPP 🔍)). I have also seen refered to as the Universal World Profile ( Universal World Profile (UWP 🔍)). I wonder why there exists a change?

You write the UPP in the form of 1234567-8 9 10 11; In the example, I’m using numbers to represent position.

Table 211: Traveller Universal PlanetProfile Legend
1Starpport Quality
6Government Type
7Law Level
8Tech Level
10Trade Codes
11Travel Advisory

Positions two through eight (e.g. Size through Tech Level) are in hexadecimal format; A represents 10, B is 11, C is 12, etc.

Certain attributes influence others; For example Size of the world influence Atmosphere.

It’s not overly interesting going through each value for each attribute. Instead, let’s roll up a world. You could also use Alex Schroeder’s Subsector Generator to make a whole subsector.

With 2d6 🔍 in hand, let’s get going.

First comes Size. I roll 2d6-2 and get a 4. The world is 4,800 Kilometer (km 🔍) in diameter; Roughly the size of Mercury or Ganymede. It has a gravity of 0.25 times that of Earth. I’d need an 8 to get an Earth-sized planet.

Second, I roll for Atmosphere. Its 2d6-7+Planet Size. The dice show 3, so I have a 0. There’s no atmosphere. Earth has a Standard atmosphere; Which is a 6 on the chart. .

Next, I roll for Hydrographics. The base formula is 2d6-7. Because our planet doesn’t have an atmosphere, I roll with Dungeon Master (DM 🔍)-4. I get a 0. This planet has 0% to 5% of its surface world covered in water. It’s a desert. Earth is a 7, having 66% to 75% covered in water.

Fourth, I check population. The base formula is 2d6-2. I roll a modified 2. This planet has 100 to 900 inhabitants. Earth’s population is a 10 (or A in hex).

For government, the base roll is 2d6-7; You then add the planets population. I roll a modified 2. This planetals government is a Participating Democracy. Earth is almost certainly a Balkanized governemnt. We don’t have a planet wide government.

As a quick sidebar, there are 1d3 Factions opposing the governemnt. I get 3. It appears that this little village world has some challenges. Each faction gets a roll on the government chart and a relative strength roll.

  • Faction 1: A Company/Corporation with significant support.
  • Faction 2: None, family bonds, clan, or anarchy with some supports.
  • Faction 3: None, family bonds, clan, or anarchy with significant support.

Interesting! This tiny world aspires to democracy, but the three other factions pull heavily. Two families and one corporation all vying for control. And remember, this planet doesn’t have an atmosphere, which means there’s life support considerations.

For another sidebar, let’s roll up their Cultural Difference. I got: “Degenerate – the culture is falling apart and is on the brink of war or economic collapse. Violent protests are common, and the social order is decaying.”

It looks like life on this world is unravelling.

Next up is rolling for Law Level. The base roll is 2d6-7, plus the Government roll. In this case, I’m rolling 2d6-5. I rolled modified 2. At this law level, people can carry military weapons and wear combat armour. Rural America for a white man.

During play the Referee can use the Law Level for helping determine random encounters with the law. Checks can be when the Travellers first approach the planet, wander the streets, act suspiciously, get in a brawl, fire shots, break and enter, engaging in a firefight using armour and military weapons, and/or murder and carnage. The higher the law level, the more likely law enforcement shows up.

Assuming a run in with the law, there’s also quick rules for sentencing. Travellers or others can use the Advocacy skill to reduce sentencing or legal consequences for their actions.

I find this to be a useful section, but these days look at it through a different lense. When playing check with your table about these rules. With police violence and impunity this may be something to leave out of your game experience. But check with your table.

I think the rules add some versimilitude, and it may be a case where you go straight to the dice and not role-play out a triggering scene where the police stop and frisk the characters for walking the street.

Next let’s roll the starport. The base roll is 2d6. And I subtract 3 because of the small population. I roll a 3, and this planet has an E-class starport facility. It’s a Frontier facility with no berthing cost, no available fuel, nor shipyard facilities, nor chance for bases.

Let’s quickly check if they have a gas giant; Without a gas giant, refueling options in this system are going to be bleak. I roll 2d6 and need a 9 or less for there to be a gas giant. I roll a 4, so there’s a gas giant in the system.

Next up, Tech Level. I roll 1d6 and modify the roll by several modifiers.

First off, because there’s no atmosphere, this world must have a minimum tech level of 8. The modifiers for the roll are:

  • +1 for a size 4 planet
  • +1 for no atmosphere
  • +1 for a 0 hydrographics score
  • +1 for a 2 population score

By my math, that’s 1d6+4. I get a 5, but bump this up to an 8. I could see a case where you keep rolling until you get at least the minimum. Alternatively, roll once and take the greater of the roll and the minimum.

TL 8 (Pre-Stellar): At Technology Level (TL 🔍), it is possible to reach other worlds in the same system, although terraforming or full colonisation are not within the culture’s capacity. Permanent space habitats become possible. Fusion power becomes commercially viable.
Traveller: Core Rulebook p6

Bases are determined by Starports. The Navy, Scout Service, Traveller Aid Society, and Research factions don’t see fit to have a base at this location. In past versions, you may have also rolled for a pirate base. But in those past versions, pirates would also not setup a base; There’s just not enough traffic.

Finally, we consult the Trade Codes table to see what might be of interest.

Summary of World Creation

Let’s call the world Daelisar; It has the following trade codes:

Low Population
A population of only a few thousand or less.
No atmosphere.

With that, I’m done rolling up this world. It’s UPP is: E40022-8 Lo,Va G.

Our little world with its small participatory democracy appears to be on the verge of collapse; Somethings going wrong. Let’s look a bit more at the Technology Level roll. I bumped the tech from a 5 to an 8. Maybe the technologies that keep this location viable are failing? What’s the original role of the corporation for this world? Who are the families? Are they the only ones? And local law allows near military weapons as part of your every day carry.


I’ve said this often, the tables in Traveller do a lot of world building. And in this chapter, it’s especially true.

In the next chapter, we’ll quickly walk through Traveller's Sindal Sector ; A sector set in the Third Imperium, but ripe with ideas to plunder.



I wrote up a visit to Daelisar by the characters I rolled up. They secure passengers, freight, and some illicit cargo using the Traveller trade system.