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Mutable Maps Part 1: Dungeon-Scale

During this last weekend’s Wandering DMs episode, Dan mentioned wanting a way of having overland maps that can change randomly. I don’t know how to do that in an automated fashion (yet), but the idea was extremely intriguing to me because I have had fun in the past with incorporating random elements into smaller-scale maps. This series will be about describing what I have done and musing over how to scale it up for overland use, hopefully coming as close as I can to Dan’s ideal.

To set up a foundation, let me go over what I have done and see if I can extract some core concepts about how it works.

I first got the idea of having dungeons that can change in uncertain and mystical ways from the Silent Hill game series. In those, the protagonist often runs into discrepancies in geometry between the “fog” world and the “other” world. Sometimes, the discrepancies are obstacles, like openings being replaced by solid walls or roads being sundered by untraversable gorges. Sometimes, the discrepancies aid the player by giving them access to new areas. Regardless of whether it’s a bane or boon in any particular instance, though, the whole experience serves to give the player a constant sense of uncertainty and unease, never quite being able to feel in control of their environment (at least not until one plays the game enough to know what’s going to happen).

Taking that straight to the tabletop isn’t without potential pitfalls, though.

First, TTRPGs have two issues that Silent Hill games don’t: NPCs that can be interacted with in unscripted ways and multiple protagonists.

Denizens of an area subject to these changes will notice it. Whether they notice it in the same way as an external “normal” observer, whether they understand what’s happening, whether they even have the awareness that there was an actual change, those are all going to have different answers for different situations. The responses of a simple farmer who stumbled into a realm of nightmarish madness should be quite different from the responses of a creature of Chaos who is used to swimming through the raw fluid of imagination or from the responses of humans in a village that blinks out to an alternate dimension for one out of every one hundred years.

PC parties tending to have more than one character means an ever-present (if oft-ignored) chance of getting split up. Should that happen, depending on the nature of the map’s mutability, it can raise the possibility of one group being in an area that’s changing while another isn’t. Can they see each other during the change? Can they interact with each other? Would the external party go to the same region as the internal party if they enter the area after the change, or would they go to a separate subspace? No matter how much the GM thinks they’re prepared, never underestimate players’ ability to throw new problems into the mix.

Rather than having a list of points to know for both of those issues, I prefer to take a similar approach as I do for traps and handle those questions by understanding what is going on (in the fiction of the imagined world) and how the denizens interface with that. That way, the GM can just roleplay the NPCs to answer any questions, and knowing how the NPCs deal with it will inherently lay out the groundwork for how to approach it when the PCs aren’t all affected by the phenomenon in the same way.

Another potential pitfall is the lessons that the players take from the experience. Once the players realize what is happening (or at least that something strange is happening), they’re likely to experiment and to try understanding how it works. That is all fine and good, though frankly, it may not even come up if the map mutation happens infrequently enough that the players never experience it firsthand. However, if they do surmise that there is some element of random alternation happening to the map, they might conclude that mapping (that location or in general) is pointless. The rarer that mutable maps come up, or the more the players can be forewarned of an area with mutable maps, the less likely they are to reach this conclusion. However, it’s always a possibility. If the GM doesn’t want players to learn that lesson, mutable maps either should be rare or should not be a surprise, if not both. That way, even if they pick that up subconsciously, it shouldn’t be reinforced often enough to become ingrained.

All of that having been said, how do I handle the mechanics of mutable maps? Well, for most cases, it’s not so different from any other randomized elements.

If the variable is the presence of a portal or a wall, it’s simple enough that I don’t think any explanation is needed.

If the variable is a room, I have a fuzzy space on my map, and I have a table of possible rooms that I roll for it when necessary (assuming there isn’t some overriding deterministic logic to what should be selected). If the selected room doesn’t quite fit the allotted space, that’s a problem for the players to figure out. Since I try to keep up some time pressure on strategic supplies (be those the rations and torches of low levels or spell castings and limited-use magic items of high levels), the players tend not to have the luxury of mapping out everything in meticulous detail, so minor inconsistencies with the surrounding geometry often get shrugged off as mapping mistakes (especially if the players don’t suspect that the map is mutable).

If the variable is a room and I want to get fancier, I’ll usually tie it to drawing from a deck of cards. One of the nice things with this is that I can codify results for both the suit and the value, giving a huge amount of flexibility without requiring multiple rolls. This can work even better if one of the PCs uses cards for divination, since that can give opportunities for the mechanics at the table to reflect the acts of the characters, but I digress. This is also great for magical mazes, particular if there’s a mechanism to add the drawn cards back into the deck, but again, I digress.

Any other variations that I’ve tried can be boiled down to the same approach. A sinkhole in a street is essentially just an impassable room. A group of rooms is essentially just a big room with internal divisions. A hole in a wall or floor is essentially just a different form of portal. And so forth.

Looking over all that, these seem to be the key takeaways:

  1. The mutability should have some in-game logic that the GM can understand, even if that logic is just random chaos.

  2. The frequency and extent of the mutability should be defined in a way that doesn’t interfere with the GM’s ability to run the game. What this means exactly will vary from one GM to another.

  3. If interacting with changes to the map is something the players are expected to do, they should have opportunities to learn that it is happening. Whether this can come from sources in the game or only from firsthand experience depends on the previous two points.

  4. The changes need some framework or procedure for the GM to pick what to do to the map.

  5. The map needs the flexibility to handle the changes without disruption to the flow of the game. The players’ resulting confusion might disrupt the flow of the session, certainly, but in terms of both game mechanics (e.g. rolling to select the change) and game logic (e.g. not ending up with a hole within a hole, except in settings where that’s possible), it should be smooth.

Honestly, none of that seems to be beyond what someone without experience running dungeons with mutable maps could’ve come up with. That’s disappointing. Maybe my experience can come into play more when it comes to thinking up what seems reasonable to do on a larger scale.



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