Dungeon Master Support in Emacs

The overlap between Emacs and running a Dungeons & Dragons campaign is… expected? Jotting notes and plans in an org-mode file has been great, but what if, during a game session, my notes became more interactive? I started creating some helper functions, which has now become a minor mode I use as a sort of layer on top of Org. Let’s blame this insanity on the pandemic, but it has been fun.

The primary interface is f6 which calls up a sticky Hydra to call my functions, but still allowing full cursor movement (mostly):

Note: The screenshot isn’t accurate, as I will change the code more often than updating this image.

Themes

What emerged from some late night hacking is more than just a dice roller, but I may have to explain my rationale.

Yes/No Complications

The FU Rules believes a attempt with randomness (what D&D calls an ability check) shouldn’t be just a yes/no, but could have some complications, like “yes, but…” or “no, and…”. Those rules used a d6 with six variations:

no, and … (failure, plus a new complication)
no
no, but … (failure, but a glimmer of something positive)
yes, but … (success, but with a complication)
yes
yes, and … (success, plus a bonus)

I love this idea, and thought that I could extend it to d20 skill check rolls. Perhaps 1 and 6 happened pretty infrequently, followed by 3 and 4, and 2 and 5 happen most often.

According to this essay, the standard DC 15 skill check is actually too hard for most situations, however, I don’t trust my bias when choosing a value for a difficulty check. For the life of me, I can’t find where I saw this idea, but you could choose a number of d6s for the challenge (1 is easy, 2 is moderate, etc.) and then add 7. That sounds pretty good, so after calling for a check, I can enter it, and Emacs confirm the results.

I want to be able to wrap both of these ideas into a single interface.

Oracle

The Victor’s GM-less Oracle game, has an interesting way to make decisions that I thought I would code. Essentially, you can have a good, middle and bad situation (that you pre-determine), and the oracle roll tells you which it is. While the idea is to generate a bell curve, it attempts to heighten the tension with some rolls adding a cumulative modifier.

I’m not sure if I will use this in-place (or in addition) to the previous luck-with-complication idea.

Random Items

As a DM, we often have to invent unplanned details to our story…especially names, but even the trinkets in the goblin’s pocket. Most DMs make lists of things, and some even pin some of these to their DM Screen, so they can look a player in the eye, and say, “My name is Samuel Gustgiver, I work at the bakery, but my friends just call me Sam.”

I wanted to create a directory full of files containing tabular goodness, and have a function that would read all the files, and then allow me to choose a random item from anything on the list, for instance:

And then having the results show up easily:

Oh, and when the players ask what the name of that strange NPC was, I made a function to display the last randomly displayed message.

Writing a function to read all the items in a list is pretty trivial, printing out a random name would be nice, but some items on these lists may be more prevalent than others. For instance, what if half the people in Waterdeep belonged to a faction, and I wanted to help my NPC’s backstory with a random faction, but wouldn’t some factions be more prevalent than others? Same with occupations, as our players would run into more docker workers than workers of magic.

A file of lists can include a frequency, for instance:

- Xanathar Guild     :often:
- Church of Talos    :scarcely:
- The Kraken Society :rarely:
- Bregan D’aerthe    :seldom:
- Bull Elk Tribe     :seldom:
- Cult of the Dragon :seldom:

But how much more often is often? So, lists are purely randomly distributed, but other frequencies are pre-calculated, as in:

4 – often
3 – seldom, sometimes
2 – scarcely, scarce, hardly ever
1 – rarely

So often is four times likelier than rarely. I also have this list:

10 – common
6 – uncommon
4 – rare
2 – veryrare, very-rare, very rare
1 – legendary

Where common is ten times more likelier than legendary. Actually, after all the work in getting this working, I’m not sure how often, in an epic fantasy game, where rare should be commonplace for the player.

The best part of this project is my collection of tables, however, I’m not sure what content falls under fair use and what is proprietary, so at the moment, create a tables directory when you clone this project, and start adding your own files.

DM Screen and Roll from my Notes

Finally, I wanted to quickly bring up a collection of rules and tables along with my session notes, a bit of a DM Screen for my screen.

Two things I noticed about org files, is that I could initially hide unnecessary meta information and focus on just the contents of the file’s table or list by prepending this blurb:

Keep in mind, that this is only good for more static files that don’t change, as I have to figure out the range.

The second thing I realized is that Org’s links can call Emacs functions. This allows me to have a bit of random-ness to a table’s list, for instance:

[[elisp:(call-interactively 'rpgdm-skill-check-easy)][Easy DC]]

My initial ideas for listing a bunch of random NPC names and having a link that displayed one of them, got supplanted for the ideas I described above.

Code

What do I have here:

rpgdm

Primary interface offering:

rpgdm-mode, plus a Hydra interface for easily calling the rest of these functions.
rpgdm-yes-and-50/50, flip a coin and make a give a result with or without complications or bonuses.
rpgdm-skill-check, given a target and a d20 dice result, returns yes/no, but possibly with complications or bonuses, depending on how well the result is.
rpgdm-skill-check-easy, queries a rolled results, and returns a complicated yes/no for an easy skill challenge, where the average DC is 10, but it could be anywhere from 8 to 13.
rpgdm-skill-check-moderate, same as above, but for moderate challenges where the average DC is 14
rpgdm-skill-check-hard, same, but for hard challenges where the average DC is 17 (with a range of 10 to 25, but with a pyramid bell curve, the average is likely)
rpgdm-skill-check-difficult, for challenges where the average DC is 20 (range from 11 to 30)
rpgdm-skill-check-impossible, the average DC for this is 24 (with a range of 14 to 35)

rpgdm-dice

All the random number generators, plus:

rpgdm-forward-roll to move point to the next dice expression
rpgdm-roll randomly evaluates dice expression at point, or queries for one
rpgdm-roll-advantage / rpgdm-roll-disadvantage rolls a d20 with a modifier

rpgdm-tables

For randomly displaying choices from a directory of tables. Call either:

rpgdm-tables-load and point to a directory of text files
rpgdm-tables-choose and choose from one of the tables dynamically, and a result is displayed.

rpgdm-screen

Still working on this one

rpgdm-screen: to display some tables in buffer windows on the right side of the screen.

Complicated details of the code is stored as literate files in the docs directory, specifically:

rpgdm-tables-freq: Parsing frequency tables, entries with labels for stating how often the occur.
rpgdm-tables-dice: Parsing standard tables with dice ranges, so copy/pasting from rule books just work.

I’m also intrigued with rulesets that are unique, for instance:

FATE: Easy character creation and a nice bell-curve dice roll, but it requires special Fudge dice, that are easy enough to recreate in Emacs. See fate-srd.com for details about this game.
Mythic RPG: A nice RPG for solo play as it has a GM-less option that I wanted to capture, see Wordmill Games for details.
Ironsworn: Another good solo RPG, I wanted to capture its quick check resolution. See ironswornrpg.com for the free rules.

benmccown / emacs-rpgdm