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Mutable Maps Part 2: City-Scale

Last time, I tried to extract some guiding principles for implementing mutable maps based on my experiences with mutable dungeon-scale maps. This time, I’ll try connecting that to my experiences with mutable city-scale maps to see how well the principles hold up and to see if any new trends come to mind.

First things first, though, what exactly is city-scale?

When I use that term, I don’t really mean anything to do with physical size. On a dungeon-scale, the PCs have a highly restricted and interconnected environment, which (should) both limit their options for mobility and increase the potential for reactivity by NPCs outside of their immediate surroundings. On an overland-scale, the situation is reversed; PCs will have nigh-unrestricted options for how they move about, and their actions in one spot won’t often impact what happens in the next location they can reach.

The city-scale in somewhere in between those. The PCs don’t have to worry about locked doors or pit traps (generally), but they still have to deal with streets, canals, bridges, etc., and there may be societal limitations on their use of magic or destructive renovation. Their actions may not draw immediate responses from nearby, but news (or at least rumors) of what they’ve done can spread and come back on them in the future. The timescale of resolution can switch fluidly between moments and hours without harsh transitions. It’s difficult to nail down in absolute terms, but much like Neutrality is a balance of Law and Chaos, city-scale has elements of both dungeon-scale and overland-scale while being distinctly different from either.

How to handle mutability on the city-scale depends on how exactly any given GM is running content on a city-scale. As I’ve mentioned before, I tend to run cities with an abstracted district-based map with defined travel times between connected districts, so that’s the baseline I’ll use for the following discussion.

Against this sort of background, mutability can manifest as mechanical impacts on both random encounters and mobility.

For the random encounters, the PCs will occasionally be faced with geographic changes that don’t (necessarily) have an appreciable impact on their immediate task at hand. Perhaps there’s a new monolith splitting an intersection or an odd influx of people from an unconnected district. This is generally more subtle than impacts on mobility, and the players are unlikely to face any direct consequences if they don’t engage with it. I think it’s still important to keep this up to some degree, though, since it sets the seeds for grander weirdness, but I’m a proponent of including foreshadowing and hints of future details when reasonable. For cities where these sorts of changes are a commonplace occurrence, I’d include them in random encounter tables from the start and/or have alternate tables ready for use after a map mutation, albeit probably at a low likelihood of happening (as I’m also a proponent for using multi-die rolls in city-scale to better shape a district’s encounters to match its content) unless I want it to be a dominant feature.

For affecting mobility, the exact implementation should vary depending on the details of each district.

If it’s someplace with controlled bottlenecks and limited freedom of mobility (like a district of noble residences, where walled compounds and heavy security presences are normal), there might be a random chance that a specific location is completely inaccessible; the PCs consume the usual travel time in searching around before concluding that they’ll need to put in an unusual effort if they want to reach their goal.

If it’s someplace where people are mostly free to move about as they will (like a slum or localized shanty town), it might be a die roll to see how much extra time is needed to find their way around as the PCs have to deal with new buildings, disappearing alleys, and so forth. Of course, nothing necessarily precludes the shanty town from having inaccessible areas as well; my simple shortcut for modeling this is to treat the time delay as an exploding roll and rule that a local is temporarily inaccessible on consecutive maximum rolls.

As with most examples on a spectrum, the majority of cases tend to fall in between the extremes, and my approach in these cases is trying to find a good compromise. For instance, if I’m using a random delay of 1d6 hours across all districts, maybe locations in an “average”-mobility district are inaccessible if they roll a delay of 10 or more on an exploding roll. Going from 1-in-36 for the shanty town district to 1-in-12 odds of being inaccessible in the average district is enough of a jump that it ought to produce a different feel in play, but it’s still low enough that it’ll feel less restrictive than (for instance) a flat 1-in-6 chance of places in the noble residence district being inaccessible.

Of course, dice aren’t the only way to decide these matters. As I mentioned in the last part, drawing from a deck of playing cards can also be a useful approach. Assuming a full deck with jokers and drawn cards being reshuffled, maybe shanty town locations are inaccessible on a joker (1-in-27), average district locations are inaccessible on a joker or king (1-in-9), and noble residences are inaccessible on a joker or face card (7-in-27). Meanwhile, maybe black draws are simple geography changes while red draws also include an NPC encounter. As ever, the exact mechanics can be adjusted to suit what the GM desires for a specific region, but that’s a quick and simple approach that could be much more efficient if the extra versatility of playing cards is taken advantage of.

The more important element for affecting mobility is how it is conveyed to the players. Simply saying “it takes you about three hours more to find the bar than you’d expected” is rather worthless; nothing about that makes it feel different from any other delay. Saying “you turn to go down the alley to the bar, stopping yourself just short of walking into a stone wall stretching up to the sky, and it takes about three hours to find another way around through the maze of buildings towering around you” is better, though I’d argue that an even better approach would be to just mention the wall and present an opportunity for the players to engage before finishing the resolution. As I’d mentioned in the previous post, the GM should understand the in-game logic of the mutability. This is where that comes to life, both in terms of how it gets described and how the players can interact with it.

The above was all talking about general locations within the city. When it comes to something specific, there’s no reason why it has to include a random roll/draw/whatever during play. I’d encourage planning mutability for major locations between sessions, particularly if buildings can move between districts (this can still be randomized, of course, just with the random element being resolved ahead of time). This gives the GM more ability to model changes in NPC behaviors based on map mutations, particularly if NPCs should know about the changes without being surprised, and it also gives more time to prepare any updated map keys or random encounter tables, if necessary.

Changes in connections between districts can be either the simplest or hardest mutation to model, depending on the circumstances. If connections remain more or less constant (i.e. any disruptions are sufficiently local that it can’t progress to a complete blockage), just use the delay mechanic of whichever district the PCs traversing for most of the trip. If connections can be disrupted or rearranged, however, that gets trickier. In such a case, I’d definitely recommend working out the changes at least one mutation into the future (depending on how likely it is for more than one map mutation to happen in the course of a single session). Check the connections between any districts where they can be changed first, and then figure out what’s happening in the city as a result of that.

Incidentally, these types of considerations are a big part of why I favor using a district-based layout for city-scale play instead of trying to map out individual buildings and thoroughfares. Working out changes on a handful of abstract districts is far easier than doing so with dozens if not hundreds of minute details, particularly if there’s a low chance of any given individual change mattering in any given session. Since I like to keep a table of travel times between districts, it’s pretty simple to update that as needed and just rely on randomized mechanics to fill in the fine details during play, and making updates to a map of broad-strokes districts is easier than doing so with a map that tries to look realistic.

That all said, it’s my goal to eventually reach an approach for overland-scale mutable maps that can be seen on a hex map, so I shouldn’t ignore that aspect entirely. So, next time, I’ll step outside of my comfort zone and think about what I might do if I wanted city-scale mutable map that doesn’t rely on a district approach.

Part 3 (to come)



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