Let's Read “Traveller: Core Rulebook”

A New Look for an Old School Game

Welcome to the inaugural post in a series of posts in which I read “Traveller: Core Rulebook” by Mongoose Publishing.

Interested in reading along? Grab a copy of the Traveller: Core Rulebook.

Various incarnations of Traveller have been in print since 1977. In 2008 Mongoose Publishing released a System Reference Document (SRD 🔍) for Traveller. From that document, in 2016 Samardan Press released the Cepheus Engine.

What this means is that there is ample Traveller “canon” as well as ample supporting material. It also means that rules development can continue regardless of copyright holder intention.

As someone who has published a few RPG supplements, I find myself leaning towards Traveller over Stars without Number. The Open Game License (OGL 🔍) provides some assurances that I can continue building from an open-source rules set.

According to “TSR, Inc. v. Mayfair Games, Inc., 1993 WL 79272 (N.D. Ill.)”, the words used to describe the mechanics may be protected by copyright, however the underlying mechanics are not; Note, they could be Trademarked or Patented, like Magic the Gathering’s “Tap” concept/symbol.

By creating the OGL and SRD, we have clear instructions on how to share the game mechanics AND the language used to describe those mechanics. In other words, once something is released under the OGL, I continue to have a right to share the developments I make against that common document.



A multitude of universes await players and you will find Traveller is capable of handling almost any kind of science fiction setting, from highly intricate cyberpunk worlds to campaigns spanning entire galaxies where mighty empires clash and suns explode.

A tall order, let’s see how it delivers.

The Third Imperium

A quick introduction to the implicit backdrop of the core rulebook. This four paragraph section reminds me very much of the assumptive Greyhawk setting for Dungeons and Dragons.

I love running sandbox games and creating my own locales. I appreciate having a distinct separation from setting and rules. I think a good rules system needs a presumptive setting, but shouldn’t rely on that setting. I’m thinking of lifepaths in Burning Wheel. The rules of character creation help shape a shared understanding of the game world in which you’re playing.

Players and Travellers

A quick separation of the player and the character; In this case the Player Characters (PCs 🔍) are referred to as Travellers.

There’s also a bit about characters. We might call them Non-Player Characters (NPCs 🔍) in other systems.

The referee controls many characters. The players each control one Traveller. And player or Traveller are somewhat interchangeable.

The Referee

Maybe this should’ve come first. But, it’s still on the same page as the preceeding Players and Travellers section.

The referee presents the situations and characters to the Travellers; It is on the Travellers to respond and the referee to incorporate their responses.

Personally, I like the term referee over Game Master (GM 🔍) or Dungeon Master (DM 🔍).

Scenarios and Campaigns

A quick separation of scenario and campaign. A campaign is comprised of a series of scenarios. A scenario is a single “episode”, though it can span multiple sessions.

I know for me, that I’m always looking towards the campaign. How do we play these spanning events that interconnect and fold back in on themselves.

Campaign Ideas

Here we have four suggestions:

  • Trader - buying and selling goods, and all of the complications that arise. Firefly is a touchstone.
  • Military - military campaigns, skirmishes, and patrols. Aliens is a touchstone.
  • Explorer - travel beyond charted space and seek discoveries. Star Trek is a touchstone.
  • Traveller - a little bit of each of those; A sandbox campaign is perhaps the most analogous.

Further Reading

A quick list of books, in print and upcoming:

You can play the game without any of these, but each adds more details to your game.

Game Conventions

A quick discussion about dice notation, modifiers, and rolls.


Traveller exclusively uses six-sided dice. Its notation is 1D or 2D for 1d6 or 2d6 respectively. Throughout this series, I will likely shift between 1D or 1d6.

Technology Levels

Technology Levels measure the scientific capacity of a world and the complexity and effectiveness of a piece of equipment. The Technology Level scale starts at 0. In the Third Imperium setting, the most advanced scientists are probing the upper boundaries of TL 15, but most core worlds range between 10 and 13. Out on the fringes of the Imperium in sectors like the Spinward Marches or Trojan Reach, Technology Levels vary wildly.
Traveller: Core Rulebook p5

So, the technology level tells me generally what’s available at a given location. Compared to Stars without Number, Traveller has a more granular technology breakdown. Below is a rough translation of Stars without Number technology levels and what I see to be their corresponding Traveller tech level ranges.

Table 197: Stars without Number and Traveller Technology Comparision
Stars without Number Tech Level Traveller Tech Level Range
00 to 1
12 to 3
24 to 6
37 to 9
410 to 12
4+13 to 14

I appreciate the more granular technology levels, especially as I consider world creation.

Until Next Time…

That brings us to the end of the introduction; A quick read. Up next .