Over on Grognardia, James poises a question about how much detail to include in a setting product and states his preference for the format I used in Blackmarsh.
By far the most common format for settings is the travelogue similar to a Fodor travel guide. Fodors and other travel guide brands have been around for a while so it only logical that when the RPG Industry started publishing that they adapted the format. However while great to read, I feel the format is ill suited for RPGs. The travelogue format requires an extra level of work in order for its details to be used during a session.
Is there an alternative? Yes! It is the format pioneered separately by Judges Guild's Wilderlands and GDW's Traveller. You present a table of coded entries some terse written details keyed to a map. Both Wilderlands and Traveller use a numbered hex grid. The format doesn't eliminate all the work but does have the virtue of being more easily used during a session compared to the travelogue. It also allow to quickly see what in nearby locales making it easier to allow the characters to wander the landscape. This is the genesis of the format I used in Blackmarsh.
I want to insert a caveat here. When I talk about utility, I mean talking about writing a setting in such a way that is doesn't take any more work to use than an adventure of comparable page length. The format's utility doesn't mean all work is eliminated and especially doesn't mean that referees that like to create their own material will like it better.
The form I use today stems from the work I did for the Necromancer Games version of the Wilderlands of High Fantasy. When the project getting off the ground there was a lot of debate on how to write the new version. Clark Peterson of Necromancer Games felt that the original coded tables were not sufficient, however other than that little headway was being made. I advocated taking the terse paragraphs of the original Ruins and Islands and applying it to all entries including lairs and villages. Finally I state down and wrote Rorystone Road to illustrate what I was talking about. Clark then refined my initial crude outline and the result was the format of the Wilderlands Boxed Set. The boxed set also demonstrates the power and utility of the format. An area equal to that of western Europe is covered in at a fine level of detail in only 400 pages. Imagine how big that would be if you wrote it like a Fodor's Travel Guide. Despite its volume it is still usable as is.
The problem with the Wilderlands Boxed Set is that it was a $70 product. A pretty big commitment for a product written in a uncommonly used format. So I resolved to find a way to publish something smaller that didn't cost so much. As it turned out I got the opportunity with Goodman Games and wrote Points of Light I and Points of Light II. I further refined the format in writing those two products. Thanks to Clark's work on the format of the boxed set I added a section detailing any named Geographical entries on the map. I also added a second section which varies depending on the map. In the second section I write about any unique chracteristics or groups. For example in Points of Lights I that section is details the various barbarians and humaniod tribes. Also in both Points of Lights, I play around with different times, and different themes. Because of the compact format, I am able to pack eight different settings in two books. All of which have immediate utility at the table.
Finally this leads up to Blackmarsh which is my most recent release using this format building on the legacy of Judges Guild and the authors of the Necromancer Games boxed set.
Currently the basic outline I use consists of
Introduction - explain any meta details
Background - written with brevity
Geographical Entries - named Geography sorted in alphabetical order
Special Entries - varies by map and my be omitted
Locales - keyed and sorted by location. May include a mini-map one column width wide.
Detailed Locales - if desired for example Castle Blackmarsh in the Blackmarsh setting.