Traveller RPG Week Day Four: Worlds

Worlds. Big round (usually) things bobbing on a sea of black. Each one unique, and every one the potential destination for a bunch of trigger-happy Traveller adventurers. Classic Traveller includes complete rules for creating everything from an asteroid belt to a high-population uber-tech Capital World, but y’know what? Let’s start bigger than that. Much bigger.

The Universe is divided into Subsectors. These are whole chunks of space 8 parsecs across by 10 parsecs down. For those of you that don’t know, one parsec is about 3.26 light years meaning an entire subsector covers an area about 26×33 light years in size. Put together a four-by-four grid of subsectors together, and you’ve got a sector.

Traveller Known Space looks like this:


(Maps from the utterly wonderful

Each one of those rectangles is a sector. Let’s zoom in a touch.


Wow. Each one of those dots is a stellar system and the green lines are X-Boat routes that act as essential communication lines between the thousands of worlds which make up the Imperium.

Zooming in again.


Welcome to Capital Subsector. Blue systems have water present; white ones don’t. The letters A-E and X denote the quality of the best (but not necessarily only) Starport in the system with A being an excellent facility and E being a marked patch of ground. A Starport rating of X means there isn’t one present – find somewhere flattish and hope for the best.

The other symbols show whether the system has Naval Bases (a star), Scout Bases (a triangle) or Gas Giants (small dot in the top right) present.

Got all that? Cool. now let’s zoom out.


See that little red splotch at the bottom of the galaxy? That’s Known Space. The rest is yours, all yours. And this is just one galaxy.

That is a LOT of space. Time to fill it, and it all begins with an enticingly blank subsector grid like this one.


(Source: The Zhodani Base, an excellent place for Traveller gamers to be)

There’s a 50/50 chance of any given hex in a subsector containing a system. That’s a roll of 4,5,6 on a d6. Parts of space where planetary systems are more dense (the Core Worlds, for example) get a +1 on the roll meaning it’s a 3,4,5,6 on a d6, while the less densely packed (relatively speaking) parts of the universe  get a -1 on the roll so just a 5 or 6 on a d6 will merit a planetary system.

That’s not to say that the empty parsecs are necessarily empty as such – they might just be uninteresting, unexplored, be stars lacking planetary bodies or (best of all) have been wiped off the Galactic Charts for Unexplained Reasons. Or, of course, they might just be empty.

Once you’ve got your dots all over your subsector map and recorded the presence of Starports, Bases and Gas Giants, it’s time to generate them planets. It’s worth starting somewhere interesting and working your way outward as the need arises.

The usual process is to generate only the Universal Planetary Profile for the main world in each System, though if you have a system that’s going to play an important part in the campaign (the Travellers’ homebase, for example), it might be worthwhile creating three or more planets in the system. Either way, the steps are the same and detailed on page 15 of the Charts booklet in the Classic Traveller Starter Kit. Check the Starport Type (either already rolled, or pick a lesser (or equal) quality Starport for a subsidiary planet) then roll in turn for planetary Size, Atmosphere, Hydrographics, Population, Government, Law Level and Tech Level. Finally, note down any Trade Classifications that apply, and you’re done.

One of the reasons I favour Classic Traveller’s World Generation system over later editions is that it sometimes throws up wonderfully odd results, and it is these from which awesome adventures are made. You can have a planet with a Starport C yet a tech level equal to Earth’s in the 1700’s, or a very high-tech world with no Starport at all. You can have a Naval Base orbiting a Zero Population world ruled by a Charismatic Dictator (an insane but friendly Computer, perhaps) or an Asteroid Belt populated by billions of inhabitants. It’s the crazy worlds that make the universe what it is, don’t you think?

Just like character generation (and the rest of the rules, for that matter) world generation is damned addictive and it’s not unknown for Traveller gamers to spend hours creating entire universes of systems just for their own amusement. Most folks either don’t have the time, need or desire to spend hours doing all this manually and this is one area where it’s worth letting a computer do all the heavy lifting (though I do recommend trying it at least once by hand!). Traveller Character Generation, imho, should always be done with pencil and paper so you have time to consider each twist and turn of your PC’s career, while Starship Generation is easiest when using a spreadsheet (and a stiff whiskey, if you’re ship building in MegaTraveller). Sector Generation – that’s best done with a computer.

Thankfully there’s no shortage of world-creating applications for Traveller. Our own Alex Schroeder has created a rather spiffy Subsector Mapper which also created beautiful random subsectors for you to kick-start your own campaign.

Arguably the best Traveller Sector, Subsector and World Mapper/Generator is still Galactic (direct link to, mailing list here), even after all these years. This is a DOS program meaning you’re likely to need DOSBOX to run it. Install DOSBOX and unzip someplace then fire up DOSBOX. At the command prompt type mount c: c:\ (it’ll warn you that this is not a clever thing to do – ignore it) then cd into your gal24 directory. For example, I type c: to change to drive C, then cd user\robin\docume~1\rpg\travel~1\classi~1\gal24 – thankfully DOXBOS has auto-complete so it’s just a matter of typing the first few letters of any folder name then hitting tab.

Finally, type gal, and you’re in! Hitting Alt-Enter makes it full screen.


When was the last time you used software written in 1998?

I could go on for hours about just how wonderful Galactic is – from the included Starmaps to the multitude of options, but instead I encourage you to explore it yourself. Press ? for help and keyboard shortcuts, and you’ll soon be creating worlds, sectors and entire universes with the rest of us.

Next: Welcome to HELL STATION.

The Classic Traveller Starter Kit is currently available for free from RPGNow. It contains all you need to play Traveller including rules for character, world, sector, starship and encounter generation as well as two  complete classic adventures to kick start your own exploration among the stars. Go get it!

9 Comments on “Traveller RPG Week Day Four: Worlds”

  1. I have to say that I am comletely intrigued with your postings of Traveller. I have never been much of a science fiction role-player, having given Gamma World and Star Frontiers a go in the 80’s, with out much fervor. I tend to lean toward the fantasy end of the spectrum, but feel myself oddly drawn to this system. I have since downloaded the free Classic Traveller Starter Kit and am asking myself where will I find the time…

  2. @Illpress Don – Yes, I think Traveller is slightly addictive. I think that’s why it’s had so many editions and conversions. I dare say there is or was a conversion for most major rule systems. I think the huge draw was that even with the Imperium as a setting. The area that players can explore is so huge that every GM has ability to provide whatever types of adventures he wants without contradicting others. In all my years of playing the LBBs, the only thing was slightly annoying was the general lack of real advancement of any type.

  3. So, if I’m following everything so far, does this mean that even with the most powerful engine (which from what you’ve said appears to be 6 parsecs in a jump) it would take 2 weeks travel time just to from (long wise) one end to the other of one of these subsectors? And with the ship you developed yesterday, it would take 5 weeks?

    1. In theory yes, provided they could refuel without needing to stop at any starports on the way and could plot a route that let them maximise their jump distance each time.

      That’s pretty much how the X-Boat routes work – these are purpose-built Jump-4 ships which stop only to drop off messages, collect new ones, refuel and move onto the next station on their route. Not each jump is Jump-4, but they still manage to cross an impressive amount of space in the shortest time possible.

      1. So for an X-Boat to make the trip from one end of the Imperium to the other (say from the bottom of that appendage on the left to the bottom of the main area) we’re looking at about 40 weeks to send a message, assuming straight line travel and minimum refuel times? Wow, you weren’t kidding when you said wars could be fought and won before anyone knew what happened.

  4. Thanks for the shout-out!

    My main problem with (Mongoose) Traveller was that all my GM muscles are trained on Fantasy. I had trouble coming up with adventures I liked. Apparently my players liked it, but I felt unsatisfied. We later switched the rules to Diaspora (FATE), but that did not help me personally. When I had played enough FATE, I was again confronted with the emptiness of Science Fiction adventures. And so we ended our campaign in the Kaylash subsector…

    1. Yeah. Coming up with decent scifi scenarios is hard, and you can only go so far in Traveller by letting the players explore and trade all on their own.

      Hmmmm. I feel another blogpost coming on……

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