Both cities are somewhere between modernity and something older.
Both cities are isolated. If you draw heat, there's nowhere to run.
Both exist in the aftermath of something apocalyptic.
Both are haunted.
So let's talk, just a little bit, shall we, about Blades in the Rain.
John Harper's Blades in the Dark is a great match for the Rainy City. They almost feel like sister cities, in a way -- I suspect there is some overlap in the inspirations they draw from. They're certainly distinct places, with different moods, with Doskvol perhaps the more serious and the Rainy City, I think, the more whimsical (and sometimes even silly) of the two. Still, they share enough to make the Rainy City a great fit for the Blades in the Dark system. One of these days, I'll run a Blades in the Dark campaign set in the city -- I want to learn more about the side of town that a Blades game would cast its shadow over.
Fully developing the district and faction content for Blades in the Rainy City would be a larger project -- its systems are tightly interwoven with setting -- so this will just be a sketch.
Here are some thoughts on how I'd use the one with the other.
Let's Start with Playbooks
All the BitD playbooks work for the Rainy City. The only thing to watch out for is that the seasons could inadvertently limit a Hound if you're not careful. Fires only light normally one season out of the year (Firelight). This can be easily handled by just making sure your Hound has some combination of a bow, hand crossbow, and heavy crossbow in addition to firearms. It'll be extra fun when the Hound gets to break out the guns during Firelight, but you want to make sure the playbook is still fun to play all year round.
Law and Order, Incarceration, and Heat
There is no central Law and Order in the Rainy City -- no city-wide police force. Thus, there is no equivalent to the Bluecoats, and no central prison. But BitD has a tight cycle between Heat, Wanted Levels, Incarceration, and Entanglements, and you have to make sure it still works.
So what do we have to work with? Well, each neighborhood does have its power players. There are Pump and Wheelhouse Constables in Levee Town. There is the Admiralty in Vagabond Bay. There are the Boxmen of Embassy Row. And there are the Guilds and their heavies. Some have local, short-term lock houses to throw you in, but that's not prison.
So how does Incarceration work?
Let's replace it with Transportation.
The city is surrounded by the "Nine Swells," the storm-tossed seas that bound as far out of the city as one can sail before being lost. It is from beyond the Ninth Swell that new refugees sail out of their own stormy flooded seas into the city. Within the Nine Swells, there are regions, much as there are districts and neighborhoods in the city. One example is Rickety, the floating pirate haven. Another is the Bobber Sea, a doldrum area.
At the far end of the Bobber Sea lies Endswell, an area where the winds die, the sargasso grows thick, and ships that enter become trapped. It is filled with rotting hulks, and the currents and waves beyond it (except if one approaches through the center of the Bobber Sea by rowboat). When someone causes enough trouble to the wrong people in a neighborhood, they may find themselves handed off to the Admiralty, who happily sails to edge of the Bobber Sea and sends them on a rowboat through the sea to the edge of Endswell, dropping them off for a time.
I didn't know Endswell was there before Blades in the Dark asked me a question. But now that I've answered it, it feels like it was always there, at the edge of the Bobber Sea, and I just hadn't noticed it. This is another example of how looking at a setting through a particular lens brings aspects of it into sharper focus.
Now, you'd still need to do some tailoring of the results of the Incarceration table, but this is a start.
The Visitor's Guide to the Rainy City is filled with factions. For Blades, they need to be assigned Tiers and Hold. A full accounting is far beyond this post, but here are just a couple examples:
For the districts, broadly defined, as reflected in the Visitor's Guide, here are some district traits. If I were doing this fully, I'd actually do each neighborhood within each district separately, but for now, tentatively, I might do something like this.
I've been running games in this city for years. I know its neighborhoods, its streets, and its people. I've run an entire faction-driven campaign (the founding of the Rainy City's first parliament), where I tracked factions and their interactions backstage.
But I've never thought about certain aspects of the city in exactly the ways I've thought about them in writing this post. Using a game system to run the city reveals things about it, and I can't wait to hear what you discover about the place by running it in your way, with your group, with your favorite game.