OSR City Prep Methods

Thought I’d open a thread on how to prep an old school city sandbox. I’ve been reading a bit about this recently

Been looking for methods on this and gone through a bunch of different places, maybe you guys have some thoughts.

I read through Alexandrians prepping the city, as well as his more recent city crawl idea posts. They were good but lacked a cohesive glue that I felt could carry a game session forward. Also it seemed rather heavy on prep that wasn’t that gameable.

I really liked this post about sandboxing by Dweller of the Forbidden City about sandboxing, which happens to include a city. Made me realise a more prep efficient way of making a city would be to provide tools that aid improvisation (common sandbox advice). Except I don’t like improv. Or at least, I’m shit at it. Maybe a better way of saying it is that I don’t yet know what tools I need to give myself to make closing the gaps at the table actually fun. An important thing I picked up from this post is that making stuff up on the fly is 100x easier if you do it in response to player actions. Easier to indulge a player looking for a seedy tavern by saying “yes you find one” than it is to make something interesting up off the top of your head. Still don’t have a solution for when players say “I want to look around for anything interesting.”

In addition to this, I started playing Blades in the Dark, which is all about generating missions on the fly. That game has amazing tools for ensuring missions you generate on the fly end up being satisfying gaming experiences (clocks, mixed success rolls) but I like old school location based adventure. How can a low prep city mix with mid-prep location based adventure while providing a sandbox environment that doesn’t involve a ton of wasted prep?

I’ve most recently landed on Into the Cess and Citadel, which has done wonders. Really helped frame the city as an actual gameable procedure, but I’ve always felt that crawling hex by hex is not really a city thing (though I do love how the street dangers in Cess and Citadel really make the city feel like an alive, bustling place). What I really love from this is the transformation of encounters from random things that bump into players to motivated actions taken by factions in response to player activity.

Keen to hear what you guys have read or methods you’ve used to make the city feel more important than just “the place you go to rest”. I’m gonna leave a comment on this thread detailing a method of prepping an OSR city sandbox, share your own stuff too!


The main thing I’ve gotten from Cess and Citadel is changing the way encounters work. Rather than being random, the city is defined by reactive encounters driven by what the players have done. For example, you don’t just run into thieves on the street randomly, they find you after you flaunt your cash in a thief-riddled area of town.

Overall, what I’ve observed is that city games tend to focus on

  • Factions
  • Showcasing Bustling Activity (typically not present in hex- or dungeon-crawls)

Using this as a base, my current idea of sandbox city prep is thus:

  1. Prep a web of faction relationships
  2. Prep a list of actions each faction can take (like sending thugs, confiscating property, etc)
  3. For each relationship between factions, prep about a hex worth of material that features a manifestation of that relationship (maybe it’s a dungeon, or just an NPC, not yet sure which is the best amount)
  4. Form rumors based on these relations, keep track of which factions know which rumors
  5. When the players get lured into doing something about one of these relationships, affected factions can respond (taking from the list of actions)
  6. Given what factions know about each other, the actions taken in response should hopefully drive the players forward into new places.

I’m gonna post about this on my blog when I’ve tried it out to see if it’s any good. This feels tangible enough to make a whole game around and only needs as much prep as maybe one region in a hex crawl, but it might turn out it needs something else. Will update.

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I typically use Voronoi Diagrams for my City Crawls. I just prefer the more organic nature of them, and how they generate those distinctive “regions” or “neighborhoods” that I can assign their own Character and Encounter Tables.

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This is awesome. I assume you key each segment or something like that? What time scale do you use for movement through the city?

Yep. Each of the Polygons gets some distinctive flavor and Encounter Table, I also like adding Smells, and maybe something from my These City-Dwellers Are… table. My Normal Human table comes in handy if I need more NPCs and I sometimes repurpose that for Businesses or Buildings as well (because my other table for that is more geared to those smaller villages.

As for the scale, that can depend on the Size/Scope/Density of the Place, but for most I tend to stick with a more nebulous “City Turn” and tie it to Procedural Checks. Smaller places just take longer to navigate than their larger counterparts. Precise times work a little better in places where there are reliable time-keeping methods like Clocks and so forth, so if those are present in the Setting it might be Hours, but otherwise you’re going to have to derive the time from things like Bells that are run at Religiously significant Intervals.


Recent table might also be useful for this: Some City Streets


These tables are just as great as always!

I’m currently prepping a small Swyvers campaign, so your smells table will be especially handy. Maybe a few are a little too clean, but I’m sure I can fill in those spaces with some grot and grime!

I really like that idea of using those Voronoi Diagrams, but will probably fall back on pointcrawls. That’s sort of how I navigate real cities in my head; from landmark to landmark - and then the inevitable confusion when I discover there’s always been a street which was a more direct route than going via memory. I’m thinking on my treasure tables I’ll put knowledge of alleys and passages which have faster traversal but have greater a encounter risk/disadvantage (emerge, reeking, from a sewer pipe, for example) as well as less kindly locals. Maybe I’ll wrangle the points into broader districts too.

Can I ask how long do you usually count a “City Turn” as? I always struggle with time keeping and feel like a bad DM when I have to handwave it. It does help there are no clocks in the setting, at least not publicly viewable. I’m just to keep the city living and breathing with varying daylight/evening/night encounters - and to make my players feel the anxiety I get going round perfectly safe London boroughs after dark! Any advice much appreciated.

There may not be clocks, but there could be other Timekeeping methods (like Bells ringing at certain religiously significant hours, the sun overhead can break the day into some “portions” of a sort.)

City Turns are general things, not really a precise amount of time (kind of like a Dungeon Turn, some are longer than 10 minutes, others are probably shorter…but it usually evens out.) I think it would vary a bit based on the size/character of the City a bit though. A massive metropolis with ancient crowded and confusing streets might take an Hour to wade-through one neighborhood to another, while something laid out more efficiently could be closer to that “10 minute” Turn. The Voronoi lets me abstract that a bit more, the “smaller polygons” are those denser/harder to navigate places, while the large ones have easier thoroughfares for traversal.

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Ah yeah; the sun is an excellent indication of the time of day. I also used NPC activities (putting washing out, heading home from work, getting drunk at the taverns) to indicate time of day, and I think that adds some charm. It is strange how easy it is to forget about the really “obvious” things when running a game - at least for a new GM!

Using Voronoi that way is really clever; especially with the polygon size equalling the density. That’s one thing the Swyvers book does well; there are rules for generating a city with district size (via minutes it takes to navigate) and, separately, population density. I ran my first session last weekend and was a bit lax with when I made random encounter rolls, but I did base it off the size of district (60 minutes size = 4 rolls a day the book suggests). I also found the time sheet at the back of Cess and Citadel helpful, with a d6 tracking the tens of minutes.

Anyway, here’s what I designed from the Swyvers rules (dotted lines are discoverable routes).

Thanks for the advice; really useful as always!


Hi all, been thinking on this for a while and had a couple breakthroughs I thought it would be worth sharing.

Cess and Citadel showed me it really does just come down to points of interest (kinda like keying hexes) and making people who relate to each other and have their own little problems and motivations. It seems simple but it hadn’t really clicked for me until reading the Running a City section of Cess.

I’ve also found that learning more about the specifics on how a faction operates has helped me run things at the table. It’s one thing to say “these guys are smugglers” and another to figure out “these guys move these goods at these times and avoid these guards” Pretty sure that’s dead obvious to everyone else but I was having some trouble figuring out how to translate city worldbuilding into game prep. Providing details seems to be the key.