Building Cities as Adventure Locations
Reading Cities Fixed at Last by Nael Fox over at Billhook got me thinking. On one hand, about procedures for building cities, and on the other hand, about the role cities play in campaigns of differing playstyles. Here, I'll tell you how I like to use cities, and then how to make them to suit it best.
The Gameplay
I'm a big fan of city adventures. The city-space lends itself to a large quantity of adventuring opportunities - heists, investgations, faction intrigue, robberies, bounty hunting, or even dungeon/wilderness crawls (back to that in a bit). On the model of Chris McDowall's Electric Bastionland, the city isn't a place of "downtime" - the adventure is "always on", random encounters are active and threatening, and danger is always around the corner.
The Procedure
Step 0: Concepts and Spark Tables.
This isn't so much of a step as much of a prerequisite: you need to know what you're making; this procedure won't generate an idea for you. I suggest prepping some Spark Tables, which will prove useful in filling the blanks this procedure will provide you with as well as developing the idea itself, if the one you have is vague.
Step 1: Obstructions
The base layout of the city is defined by its Obstructions: features that impede traffic. These can be natural, such as rivers or other bodies of water, hills, cliffs, or even small woodlands or marshlands, or artificial, like rings of walls, earthworks, or water reservoirs.
Place various Obstructions throughout the space the city will occupy. These might be linear in shape, like rivers, coastlines, or walls, or occupy an area, such as a forested hill. Some might be straight-up impassable, and some might be traversible with difficulty, and might even house a few secluded NPCs or even monsters (here's when the dungeon/wilderness crawls I was talking about earlier come into play). Also, make sure that the obstructions aren't always connected to one another - you'll see why in the next step.
Step 2: Districts and Thoroughfares
Choose some Obstructions along which to place Thoroughfares - major arteries of traffic through the city. Some Obstructions will be best suited to this, like rivers or coastlines; but don't put a thoroughfare on the edge of every obstruction. In the empty zones, place Districts, inhabited zones with unique traits and that, most importantly, have content that is hard to avoid. Passing in the middle of a district is possible and often the only way to get from Point A to Point B, and that's where the most relevant and action-rich encounters take place.