Assumptions in Traveller

I originally wrote this as an introduction for some players who had never played in Charted Space before. Sharing in case it’s useful.

Traveller’s default setting - Charted Space - is based upon the kind of SF pioneered by Isaac Azimov in the Foundation trilogy, Andre Norton in the Solar Queen books, EC Tubb and the Dumarest saga with lashings of Star Wars (which was released the same year), Herbert, Heinlein, and many more. The setting has subtly developed as new and different waves of science fiction have washed over it.

It is space opera with a veneer of hard SF.

It is not the only setting that you can use; the tools in the game are quite flexible, as has been shown with 2300AD, Judge Dredd, and the forthcoming games of Pioneer and Dark Conspiracy. However, it is the default.

The key features of the setting are:

1) FTL - Faster than Light - travel

This uses the 'Jump Drive'. Fueled with liquid hydrogen, the jumpdrive sends a ship into jumpspace, where it cannot be contacted. The ship stays in jump until it reaches the exit point plotted or it intersects with a large mass. A jump always takes a similar time; 168h +/- 10% (a week).

Jump drives are rated with a number. This represents the maximum number of parsecs a ship can travel in a single jump. A parsec is 3.27 light years.

Jumping near gravitational masses can cause a catastrophic mis-jump. Ships fail to emerge from jumpspace, or emerge many parsecs away from their destination, and sometimes in the future. The ship is surrounded by a jump-bubble when in jump space. The effect of the jump bubble is potentially harmful to humans exposed to it. Cases of madness have been reported.

2) Communication is limited to the speed of jump

Like the age of sail, messages are carried by ships. There is no FTL communication like subspace radio in Star Trek. Ships and agents operate independently as a result; you can’t call Starfleet for backup. 

3) Power is cheap and high efficiency

Fusion power is common and can be quite small. It is certainly seen as safe. 

4) There is no conscious AI

Computer technology is less well developed and AI pretty much unknown unlike settings like Iain M Banks' Culture or Neal Asher's Polity. The Imperium actively suppresses such technological innovation, but maintains research into the technology and has deployed it (for example when experimenting on creating much more heavily automated starships). Conscious AI eventually escapes into the wild, having been weaponised, and brings about the final destruction of the Imperium as ‘Virus’.

5) There are multiple Polities, many of them Human

By default, the game is set in the Third Imperium, a feudal empire that controls the space between stars but allows each world to govern as it chooses, so long as Imperial laws are not broken. The Imperium is surrounded by multiple other polities, several of which are human, but there are also alien polities.

6) The Ancients dominated the region previously and had technology far in advance of that used in current times

Several hundred thousand years ago, an extremely advanced culture developed and tampered with the future of the species in the region. They destroyed themselves in a cataclysmic war and are the subject of speculation and exploration.

7) Psionics exist

Psionic powers (mind powers like telepathy) exist and different polities take different approaches to them. The Imperium suppresses psionics officially, but it is at the heart of the Zhodani Consulate’s culture and a cause of distrust between the two polities. Of course, the Imperium also maintains research in this space despite its ban on the techniques.

8) Feudalism dominates

The Third Imperium is a feudal state, with nobles responsible to the Emperor for the systems they are granted as fiefs. The systems themselves can be representative democracies, theocracies and more, so long as they acknowledge the control of the Imperium and its ownership of the space between stars. It could (and has) been argued in the past that the Solomani Confederation (despite its one party state) is a more democratic society than the Third Imperium. Social standing is important if you want to influence and change how things are done.

9) Mercantilism dominates

The Third Imperium’s expansion was built as much upon trade & stability as it was with force. Trade demands stability, and stability requires peace. The writers for the Milieu Zero Traveller setting explicitly modelled the expansion upon the way that the East India Company operated; exploitation and violence. This upset quite a few people when it was released (as ‘not being realistic’) but it was officially signed off as canon. Although there are mega corporations that span the Imperium and beyond, there is also the space for small free traders making a living in the gaps the mega corporations leave.

In conclusion

These are the key features of Charted Space, specifically around the default Third Imperium setting. If you explored further around other polities and deeper into space (for example, the Zhodani Core Expeditions, the Solomani Rim Expeditions or the epic Deepnight Revelation mission) then you will find differences and exceptions to this, which is one of the reasons that I love the setting as much as the simple mechanics.

If you’re a Traveller fan, what other bits have I missed?

15 August 2026