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Designing Campaign Star Maps

So, for whatever reason, you want to run a Traveller campaign using your own starmap. Here is some advice from a Traveller referee, and something that I assume will cause much discussion on the list. The caveat that applies to all of this is - this is what works for me and the folks I've played with.

2D or Not 2D

The standard Traveller starmap is flat and uses hex-based movement. Interstellar space is actually three dimensional, and there aren't any rows of hexes inscribed across the galaxy. I think it's reasonable to at least consider Traveller with a 3D starmap, or even a "real" starmap. Before you go that route, there are a few things to consider:

  1. The number of possible destinations and routes grows as the cube of the distance, rather than the square, significantly increasing the number of worlds within a few jumps and making navigation harder. For example, there are no stars within J-1 of Terra. There are 4 within J-2, 11 within J-3, 32 within J-4, 67 within J-5, and 103 within J-6. A 2D J-6 map has 126 hexes and typically contains around 40 stars.
  2. Large polities are proportionally larger than in canonical Traveller materials. For example, a 3D empire with roughly the same transit time as the Imperium would, if centered on Terra, contains well over 30,000 stars, as opposed to somewhat under 10,000 for the Imperium.
  3. There is no easy way to represent the 3D map on paper for ready navigation. There are ways to solve this problem (such as pre-computed distance tables or node maps for each jump range), but in general the results look more like a computer program flowchart than a "starmap".
  4. You will probably need computer assistance for mapping and navigation, so be prepared for some number crunching and considerable work. You may need to have (or know someone who has) computer programming skills.
  5. The players may not be able to visualize the starmap or do effective navitation on their own. The referee should expect to (impartially) help with this, and should consider placing an NPC captain or navigator on the crew as a means of providing the players with accurate information and a way to select from a more limited set of choices.

My recommendation is to use standard Traveller 2D maps, particularly if you are planning to create a "large" empire. Although 2D maps are unrealistic, they are easy for players and referees to use. However, I know of campaigns that have successfully used 3D maps, particularly campaigns that stick to small areas of space.

The Big Picture

Before you start rolling the dice to generate worlds, it's a good idea to step back and draw a large scale mape that shows an overall picture of the campaign setting. This picture should include the main political entities in the game, and any other significant astrographic features such as homeworlds, trade routes, star clusters, rifts, etc. The region where the campaign is set should be identified on "the big map". It is also helpful to draw an intermediate-scale map that shows the campaign area and it's immediate surroundings.

The large-scale and intermediate-scale maps can get away with some inaccuracy; I recommend against providing exact coordinates for features on the map. If or when you make the detailed sector and subsector maps of these areas, you can adjust the exact coordinates a few parsecs one way or the other without having to fudge or re-draw your large-scale maps. The important parts of this phase is to plan out how all of the pieces will fit together. Once we get down into the nitty-gritty of world generation, it's easy to loose sight of the forest while you are busy putting the leaves on the trees.

Use of Automation

It's quite feasible to use computer software to generate dozens of sectors using almost any edition of the Traveller world generation rules. However, in my humble opinion, the campaign will be better served with a smaller campaign map that has been personally supervised by the referee, as opposed to a large map that is purely the result of a computer run. There are a few reasons for this:

  1. If the referee has hand-generated or at least reviewed each world in detail, he or she is more likely to be familiar with the details of the map, making it easier to place adventures and worlds in proper context.
  2. The referee can tweak the map (typically by modifying die rolls) to produce worlds tailored to specific campaign needs, making the map better fit planned activities.
  3. The referee can place non-random worlds (that is, worlds constructed to support a specific adventure, alien race, etc.) on the map in a sensible place, and ensure that the surrounding worlds make sense.
  4. Traveller world generation uses lots of die rolls, and the random number generation functions in most older programming languages are weak*. This will produce unexpected and odd-looking results if not reviewed and corrected by a human. For a Traveller example, look for "stripe" patterns in the non-canoical DGP sector files (I believe in Ealiyasiyw and Iwafuah sectors).

I also don't suggest placing every star system manually and generating every world by picking values. Firstly, it's a lot of work; secondly, the resulting map is likely to look like an artifact with recognizable patterns rather than the naturally-random distribution expected in a real map. For an example, look at (now non-canonical) The Beyond sector from Paranoia Press.

However, if you have a computer and Traveller mapping software available, certainly use it to store world data and generate maps as needed. It is extremely useful to be able to lay down a subsector or sector map, as well as a J-6 map for the current location, and overlay trade routes, calculate volumes of trade (as per GT: Far Trader), and generally sort and search the world data.

How Big?

So now that you've planned out the stage on which two 10,000-world empires will fight their epic conflict, the idea of generating (and personally reviewing and tweaking) 50 sectors containing 22,000-odd stars seems a little daunting ... as well it should. If you could do a star system every minute, and worked for 16 hours a week on the project, that empire would take 6 months to generate. That's a lot of prep-work for an 8-hour RPG session. So how much do you have to do before you get started?

My recommendation is that at an absolute minimum, you need to generate a J-6 starmap centered on your starting world, a 12-parsec circle. That's 127 hexes, and probably contains about 40 worlds, give or take a dozen. At 5 minutes per world, this will take less than 4 hours, and give you a nicely detailed chunk of space as a setting for your first few sessions. You will probably want to spend a few more hours detailing some key worlds in that area of space. You can use your big picture maps to decide what is off of the edges in general terms. I recommend noting where trade and X-boat routes go off the edge, and what major destination lies at the end of the off-map link. You will have to make sure that the players don't go too far from the starting world in the session, but most ships are J-1 or J-2, so it shouldn't be a problem. As players move from world to world, you will have to generate new systems in between sessions. Always keep the "edge of the map" at least 6 parsecs from the PC's current location at the start of a session.

A better plan is to generate 9 subsectors: the starting subsector and the box of 8 subsectors surrounding it. This gives you a 24x30 parsec chunk of space to operate in (a bit more than half a sector); it will contain about 240 stars and will probably take a good bit of time: each subsector will probably take 2 or 3 hours to generate if you review each world, designate sensible trade routes, and generally build a quality map. Again, plan to spend a few hours detailing important worlds in your campaign area. However, you don't have to generate new maps until the players leave the starting subsector. Once they do, generate new subsectors to keep at least 8 parsecs between the players and the edge of the map.

If you have a lot of time (or if you are fast and have good software), generating an entire sector, plus the 20 subsectors bordering it, gives an extensive campaign map. I have only had one campaign that crossed more space than this - and that only because one of the plot points was getting the expedition through a sector of semi-hostile territory. This is about 1000 stars, and will take a significant time investment - but will probably serve as the underling map for many game sessions and perhaps even multiple campaigns.

* "Weak" random number generators exhibit short periodicity (the results repeat after only tens of thousands of iterations), poor distribution (some numbers or patterns of numbers occur more often than they should), or correlation (the next number generated is related to the last number). The random number generator functions supplied with many older programming languages are particularly poor; "cryptographic" random-number generators in modern languages like Java are better.