Off the Path: City Construction, Part 1: Basics

Deviating from plan (I’d said my next post would be about building a ‘local pantheon’ of small gods), I decided to write instead about alternate rules for developing a city or other settlement.

It expands somewhat on the Polyhedral Pantheons Adaptations I wrote about a while ago.

Settlement Basics

Before diving into process, I’m going to describe some of the mechanical underpinnings. They are in some ways pretty similar to how characters are created.

Settlement Scores

Each settlement has ability scores comparable to — and associated with — the normal character ability scores.

Settlement Score Ability Score Description
Military Strength How well the settlement can deal with military and other active threats.
Trade Dexterity How much commerce is done and how well-connected the settlement is to other entities.
Infrastructure Constitution How resilient and enduring the settlement is in physical terms; includes actual infrastructure such as roads and aqueducts, and availability of important resources such as food and healing.
Craft Intelligence How much artifice, creation, and innovation are available in the settlement.
Stability Wisdom How well-regulated the settlement is, especially in the face of disruption.
Social Charisma How active and sophisticated social elements of the settlement are.

Generate these through the normal means: point buy, random roll, whatever. I favor adapting ‘27-25-23‘, making it instead ’23-21-19’:

  • Roll 3d6, subtract from 23. These are two scores.
  • Roll 3d6, subtract from 21. These are two more scores.
  • Roll 3d6, subtract from 19. These are two more scores.
  • (reroll anything that would result in a score outside 3..18)
  • Assign to taste.

I like that all settlements start with some difficulties. These will be overcome as they get larger (see below) and generally aren’t crippling anyway.

Settlement Levels

Level Qualities Population GMG size Low Pop High Pop
1 1 18 thorp       15 21
2 1 25 thorp 21 30
3 1 35 hamlet 30 42
4 1 50 hamlet 42 59
5 2 71 village 59 84
6 2 100 village 84 119
7 2 141 village 119 168
8 2 200 village 168 238
9 3 283 small town 238 336
10 3 400 small town 336 476
11 3 566 small town 476 673
12 3 800 small town 673 951
13 4 1,131 small town 951 1,345
14 4 1,600 small town 1,345 1,903
15 4 2,263 large town 1,903 2,691
16 4 3,200 large town 2,691 3,805
17 5 4,525 large town 3,805 5,382
18 5 6,400 small city 5,382 7,611
19 5 9,051 small city 7,611 10,763
20 5 12,800 large city 10,763 15,222
21 6 18,102 large city 15,222 21,527
22 6 25,600 metropolis 21,527 30,444
23 6 36,204 metropolis 30,444 43,054
24 6 51,200 metropolis 43,054 60,887
25 7 72,408 metropolis 60,887 86,108

Like characters, settlements have levels. Small, minor settlements (thorps and hamlets and whatnot) are very low-level, major settlements such as large cities and metropolises are high-level. This affects how good a settlement is at something, and the population.

At levels 4, 8, and every fourth level after that, add 1 point to all six settlement scores.

I’m going to say that a level 2 settlement has a population of about 25 people, and that every two levels the population doubles. Increasing or decreasing by one level multiplies the nominal population by the square root of 2 (about 1.4).

The exact populations aren’t particularly important, so I’m looking at ‘nominal population’ to provide an estimate.

The ‘GMG Size’ column assigns settlement type, per the Pathfinder Roleplaying Game: GameMastery Guide guidelines… approximately. This actually will have little direct impact on the process mechanically, but is useful for descriptive purposes.

When assigning the ‘GMG Size’ values I looked at the nominal population rather than the population range. For example, a level 8 settlement has a nominal population of 200. Per Pathfinder Roleplaying Game: GameMastery Guide a settlement with a population of 201 is a ‘small town’. It would seem that this would fit the level 8 settlement because 201 lands in the level 8 population range (168..238)… but I chose to not do that.

Population and Experience Points

Population of a settlement grows on an exponential scale. Every two levels the population nominally (it’s not likely to be exact) doubles.

By strange coincidence — no, really, it wasn’t planned on my part — the experience point totals needed in the Pathfinder Roleplaying Game to advance levels doubles every two levels. (Or rather, the series converges on that ratio, more or less, once you get past about 10th level… but it works for slow, medium, and fast rates.)

So it looks like population and experience points have similar enough curves that for this purpose they can basically be equated. This leads to all sorts of interesting ideas for city-building minigames that I’m not thinking about too hard right now. But I will remember for later.

Settlement Qualities

A settlement has ‘qualities’ that modify the nature of the settlement. In some cases a quality might provide a modifier to a settlement score (‘defensible’ indicates that the settlement is easier to defend from attack than most, providing a bonus to the Military score). In other cases a quality might indicate a specific resource or other benefit to the settlement.

These can be similar in concept to the Settlement Qualities described in the Pathfinder Roleplaying Game: GameMastery Guide guidelines, but as these rules use different scores they would have different effect.

My next post on city construction will cover qualities in greater detail.

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