Designing Solar Systems for 2300 AD
One of the mechanics I’ve really enjoyed over my years with Traveller and Traveller:2300 (2300 AD) is the ability to generate star systems. Still, with 2300, I feel a bit constrained by the Near Star List, and the different colonial arms . Fortunately, Traveller has a long history of designing your own setting. And with Mongoose using their Traveller engine for 2300 AD, there is a lot of compatibility to make use of.
Adapting Other Traveller versions
One of the strengths of Traveller5 (and 5.1) is it’s depth of detail. Book 2 of Traveller5.1 adds a very detailed system generation mechanic. The Referee can use these rules to create a multi-body solar system. For 2300, These system-scope locations can support a full campaign. Though for purposes of this article, the interest I’m exploring is how the solar system is developed through application of system generation mechanics.
The resources I’m using (and modifying) for this exercise are the original system generation mechanics from Traveller: 2300 (World Generation Chapter; Referee’s Manual pp 36 – 44). I’ve supplemented those mechanics with Book 3 of Traveller5.1 (Systems and Worlds pp 16 – 90). You can also find a lot of the foundational material in Classic Traveller Book 6: Scouts.
When the Solar System is laid out, the worlds Universal Planetary Profile can be generated using systems native to 2nd Edition Mongoose Traveller. The trick is generating the Universal Colony Profile.
As presented, 2300 AD is not intended to use custom generated worlds and colonies. The setting as designed presumes adventures being set in the core and frontier of the Near Star List. The Near Star List was, when the game was first designed a comprehensive map of most celestial bodies discovered within 50 light years of Earth. This map was created in the mid-late 80s (Traveller: 2300 was first published in 1986) from Astronomical data from that time.
To add a little perspective, 1986 was still four years before the Hubble Space Telescope was launched. At the time of this writing (2026), this same 50ly volume around Earth has been far more thoroughly explored because of Hubble and the J Webb telescopes. (Indeed the image of Saturn used for the masthed is pulled from the NASA website J Webb space telescope imagery.
Still, for the purposes of the 2300 AD campaign, Mongoose has chosen to maintain and develop the original setting material. Which is a valid editorial choice, no real need to rework 40 years of content.
Map Only As Really Necessary
This helpful phrase, coined by Marc Miller for Traveller5 and 5.1 is fantastic advice. Even a single solar system can contain dozens of worlds and millions of asteroids. It is really easy for a Referee to lose themselves in generating statistics for worlds that will never, never ever, be visited by a single player character. I’ve learned this lesson the hard way over my long gaming career. The detail and promise provided by the system generation mechanic can inspire long thought experiments. The designs evoke “what if” stories of who are the people who live here, or who once lived here and left behind their legacy in ruins and other footprints of civilization. If a Referee isn’t careful, they can spend weeks and months making details that will never see the gaming table.
When starting a campaign using the systems for creating worlds and colonies, restrain your design to the world where the campaign begins, and the location where the first adventure takes place. From there, new locations can be designed based on the player’s choices for their characters. If the players make a truly random choice as to where their characters travel next, there reamain plenty of already designed colonies that can be found in 2300 AD Book 2: The Worlds of 2300 AD.
Dezzy’s House Rules
These are some of the house-rules I’ve developed to adapt the existing mechanics to generate unique systems, worlds and colonies.
Coordinates: The limitations of “safe” Stutterwarp range of 7.7 light years will require most new worlds to be placed within that radius of a settled colony. For each coordinate (x, y and z) roll “Flux” using d8s (hearafter called “d8 Flux”) and apply the result to the coordinates of the system of origin.
FLUX is a dice mechanic taken from Traveller5 and 5.1. To roll flux take two dice of contrasting colors and subtract the result of the dark die from the light die. In Traveller, the flux dice are always d6, but for purposes of these house rules, we’ll be using d8.
EXAMPLE: Rolling 2d8, one being dark and the other being light, The dark die results in a 3 and the light die results in a 7. The flux result is 7-3 = +4. If the dark die resulted in a 5 and the light die resulted in a 2, the flux result would be 2-5 = -3.
Nationality: 2300 AD has developed colonial networks along “arms” of stutterwarp routes beginning at SOL (Earth). Each Arm is named for the nation that pioneered it’s exploration; the French Empire, Manchuria, and the “American” arm (mainly efforts from the United States, Texas, Mexico and Canada.) If the newly generated system has a colony, choose an appropriate colonial power for the nationality.
Colony Age: The current wave of colonization is around 100 years old, thus if the new system has an existing colony, roll d% for it’s age and maturity.
Initial Orbit and Subsequent Orbits: Modify the tables on page 39 of the Traveller: 2300 Referee’s Manual to read;
- 3d6 –Orbital Distance–Multiplier
- 3—Empty Orbit—Empty Orbit
- 4—Empty Orbit—x1.3
- 5—.1 AU—x1.4
- 6—.2 AU—x1.5
- 7—.3 AU—x1.6
- 8—.4 AU—x1.6
- 9—.4 AU—x1.7
- 10—.5 AU—x1.7
- 11—.5 AU—x1.8
- 12—.5 AU—x1.8
- 13—.6 AU—x1.9
- 14—.6 AU—x1.9
- 15—.7 AU—x2.0
- 16—.8 AU—x2.1
- 17—.9 AU—x2.2
- 18—1.0 AU—Empty Orbit
I personally don’t always leave all system aspects to the randomness of the dice. If I require a world or colony with specific characteristics I simply assign the appropriate value to the proper descriptor.
Lore and Legends of the Dezzyverse 
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