To me, a lot of the trouble that people have where it comes to "designing their world" is that they don't know what to design. The default is to design things that are very small - buildings, streets, dungeon hallways and rooms, etc. These could be termed 'microdesign' in that they serve to apply to the immediate needs of the party, in terms of what is five feet to their right and fifteen feet to their left. Useful, obviously. But apart from the immediate, these things don't help much where the party decides to march off in a direction, say a large open landscape where they're going to see two thousand acres in a day. You can design one small part of one acre, but you can't really get a sense for the scale.
What is needed, then, is 'macrodesign.' Here, I think, the game and most of the players are notably lacking, because they just don't know how to approach the problem.
To try and sketch out a method, I'm going to return to an image I once used to describe my trade system: the map of Hothior, from the old game Divine Right!
Ah, so familiar, so conveniently neutral. I am going to use this to demonstrate a system which really works better on the maps on my world, but for the general audience I think it would be best to simplify that so that anyone can apply this.
That does mean I will need to add some information to the above to make my system work. To start with, I need to give a population figure to each of the above cities, Port Lork, Tadafat, Lapspell and Farnot. I also need to establish a population for the region.
If the hexes are 20 miles across, the above region is about the same size as modern day Bosnia (without Hercegovina). Recognizing that there really ought to be more than four cities in an area this size, I'm going to identify the population at 2,000 per hex (there are 50 hexes, counting all those on the water as a full hex). Total, 100,000.
For city populations, we'll say Port Lork has 8,000 people; Lapspell, 6,000; Tadafat, 4,000 and Farnot, 2,000.
I'm introducing these numbers so that you, in your world, can take the probable size of cities that already exist. Obviously, the population isn't going to be distributed evenly throughout the countryside. More importantly, neither is the infrastructure ... and what I mean to do is produce some infrastructure numbers we can work with.
Let's take the total value of the cities (20,000) and divide it into the total population. From that, we can presume that each city influences 5x its base population: Port Lork, 40,000; Lapspell, 30,000; etc.
Let's further divide these bigger numbers by 259 (persons per square mile). We'll call this the BASE Infrastructure Number. For Port Lork it is 155; for Lapspell, 116; for Tadafat, 77 and for Farnot, 39. Let me add those numbers to the map just for convenience. In addition, I'll color code what amount is coming from which centre:
Now, let's say that for every hex away from the core hexes, the cities themselves, the Infrastructure Number is halved. Let's also say that if the adjacent hex is a forest, the number is cut to one third. If hills, the number is cut to one quarter. And finally, if mountains, the number is cut to one fifth. The number is always rounded off to the nearest whole number before calculating the next hex.
Let's just work out the hexes immediately next to the core cities:
The important thing here is that where an overlap occurs, the numbers should be added together. The hex between Farnot and Port Lork, therefore, adds 20 and 78 together. The gentle reader may also notice I didn't extend the Port Lork number into the hex adjacent to the water ... that is because this infrastructure system is measured overland, except where overland is impossible. Also, because this is infrastructure and not actual population density, the whole seashore is counted as one hex, even if not all that hex is land.
The influence of all the cities are ultimately expanded outward until they cannot be anymore. As well, each city's influence affects the actual hexes of other cities. So, even though its messy, let's expand all city's influences out to their maximum:
That's annoyingly difficult to read (and I hope done accurately) ... but it shows the pattern distributed from each of the four cities. Usually I would do one city at a time and add up the numbers as I went along, but this is for demonstration.
Let's add up the numbers to get a single total for each hex:
Now, let me stress. This is simplified from what I usually do. I usually have more cities; I have elevations for every hex which influence the total distribution and son on.
Also, I don't suggest that what we have here are any surprises. Obviously the mountains and Bad Axe forest were going to be empty. Obviously there was going to be higher numbers around Port Lork.
What's interesting here is we have exact numbers. We could say that these were % die rolls for whether or not there was an Inn in the hex. We could use the inverse number for the likelihood of bandits. Or a measure for how good the roads are. A minimum number could indicate a ferry (50) or a bridge (100). A forest hex with 60+ could have industry; 30+, gameskeepers; and less than that, thieves or brigands.
It's really up to you how you want to assign values, and what for. If you want your cities to be more metropolitan, increase the penalty for infrastructure in adjacent hexes (divide by three or four or whatever you wish for each hex out). Add a penalty for crossing a river. Roll a die and make "evil" hexes that severely lower the numbers. What's important here is that you find a way to measure a lot of blank hexes in some way that establishes a frame upon which you can build up all the little pieces I spoke about in my last post. How many points does a hex have to have before there's a hospital? A school? How little does there need to be for the party to be able to have a free hand in the area? Where does management and government hold the greatest power? You have a yardstick to give all that space a greater integrity. Call it a sort of "infrastructure perspective."
Go have fun.