Enter Three Witches: a writer-focussed game engine

Starcraft 1 followed an ingenious strategy: it used long-lived and hard to change videos only for flavor. All plot was conveyed in ingame text that could be changed by changing simple text files and in briefings that had a voice-line but no added dependencies.

The plot of Starcraft 1 was intense, brutal, and clever and its characters were powerful and a perfect match to the harsh world they inhabited. The writing was so strong that hearing a sentence like “I'm pretty much the Queen Bitch of the Universe” did not feel cheesy or cheap but showed how the power dynamics had shifted.

Starcraft 2 abandoned that. Its video cut-scenes told the central parts of the story and when I first watched a cut of those videos to decide whether to buy it, I was severely disappointed. I almost skipped it due to that. When I finally bought it, I found that the ingame story made up for the weak videos. Again that story told with ingame dialogues could be changed far more easily than the videos.

For a recent example: Baldur’s Gate 3 has some awesome writing and it managed to capture me emotionally on a level few games reached before. My level of emotional investment was similar to that when I played Suikoden – and when I played Suikoden I was around 15 and easier to impress (I think).

Baldur’s Gate 3 has fully voiced dialogues, but the speakers recorded continuously and text in all parts of the game got changed until and even after release.

What these have in common: writers could tinker till the end.

If you want to enable the best writing, then the writing must be what you can change at all times and writers must be the ones who can experiment the most.

Enter Three Witches tries to enable just that: let writers take the helm. Writing directs the plot and holds everything together. It does not build on locations that ask for some text to show. Instead it builds on dialogue that can be enriched where and when needed.

Does it work out? Read on, then give it a try.

Code encodes intent. Since it is written not only for humans but also for machines, it always sprouts some ceremony: structures and patterns that are only needed by the machine, but rather obfuscate than clarify the intent.

To minimize that ceremony, enter three witches started with an investigation how dialogue is encoded for humans. Specifically: how people digitized Shakespeare’s plays in plain text.

There are two main approaches:

• Speaker-prefix: Speaker (sometimes capitalized) starts the line with continuation indented (1993 version from Project Gutenberg) and
• Speaker-heading: Speaker (sometimes capitalized) starts the paragraph that ends on an empty line. (2025 version from Project Gutenberg)

Both always introduce people with Enter.

Example for Speaker-Prefix:

Enter BERTRAM, the COUNTESS OF ROUSILLON, HELENA, …, all in black

  COUNTESS. In delivering my son from me, I bury a second husband.
  BERTRAM. And I in going, madam, weep o'er my father's death anew;
    but I must attend his Majesty's command, to whom I am now in
    ward, evermore in subjection.

Example for Speaker-heading:

  Thunder and Lightning. Enter three Witches.

FIRST WITCH.
When shall we three meet again?
In thunder, lightning, or in rain?

SECOND WITCH.
When the hurlyburly’s done,
When the battle’s lost and won.

THIRD WITCH.
That will be ere the set of sun.

The modern format uses centered speaker names instead, but centering code on a fixed size page feels so alien to programming that I discarded that. But for completeness let’s add that.

Example of the traditional style from the Dramatists Guild (From Tennessee Williams’ Not About Nightingales):

                         BOSS
                    (removes cover from basket)
Speak of biscuits and what turns up but a nice batch of
homemade cookies! Have one young lady – Jim boy!
               (Jim takes two.)

You can see reminiscences of the first two examples in the final format of Enter Three Witches:

Enter : First Witch ;; introduce with Enter
        Second Witch ;; continue with indentation
        Third Witch

First Witch ;; speaker starts the paragraph
    When shall we three meet again
    In thunder, lightning, or in rain?

Second Witch
    When the hurlyburly's done,
    When the battle's lost and won.

Third Witch
    That will be ere the set of sun.

Since we’re also writing for computers, reading like text written for humans is an important part, but not a sufficient system to write games.

The clear syntax makes it easy to create the text to be shown, but a game is more than linear text. You need to ask questions and show a different story based on the results. Or track effects of decisions and make them affect the game. Or start a minigame.

To enable controlling those aspects, a system for game scripts can provide specialized commands, but then writers who want to go beyond the expected have to request features to be added or must change very different parts of the game, so most writers would be blocked and would have to wait for others before they could go beyond these limits.

Instead of this, Enter Three Witches embeds its syntax into Scheme, one of the most flexible programming languages.¹ This puts all capabilities of a full programming language into your hands without risk of being overwhelming, because you only need to touch those capabilites where you really need them.

This way there’s no need to wait: the writer controls what happens and when it happens, and everything that can be done via code can be done by writers. And is used just like the helpers already provided by Enter Three Witches. That gives you independence from the framework.

Everything is driven by the writing and writers can tinker from the start up to the very end.

To enable you to tinker with confidence, plot analysis tools give safety against breaking the plot. They build on the easy code introspection of Scheme to show how changes affect the overall picture of the plot.

This section helps you setup enter-three-witches (on GNU Linux) and explains how to write a branching story similar to a game book.

(show format, show conversion)

You can now tell a path through a story with decisions, but all consequences are immediate. But a story is more interesting if there are long-term consequences.

Enter three witches provides three ways to keep state: outcomes, character attributes, and wounds. All three are passed via the name state between fragments.

Outcomes are named facts like insulted-the-miller or restarted-the-generator. You can set them and check later whether they were set.

Character attributes are values attached to names of people. They come with a ruleset which allows checking whether some action succeeds, and they can improve with usage or by increasing it manually.

(in a game, many people want to see the effect of their choices ⇒ outcomes, skills, and wounds) (show analyze plot and outcomes)

• dryads wake
• dryads sun

(accessible graphics and sound for the Web-Version, setup for somewhat safe access via telnet, Deployment to Linux distros, Graphical Chickadee-Game, integration with ifarchive https://babel.ifarchive.org/babel.html, integration in arcade or strategy games, dialogue snippets for ingame banter in world exploration RPG levels, …)

(DrArneBab, PhD, reference the talk Natural Script Writing with Guile again, also reference the 2016 talk, and a previous try — TextRPG — but say clearly that I don’t have industry experience with large-scale games, so the future will show how well this works out on the long run. But at the current state I’m confident enough in the design that I dare to recommend it to others, which is why I now wrote this tutorial. That’s also why along with this tutorial I’m releasing version 1.0 of Enter Three Witches. I consider it as stable now, so future changes should preserve backwards compatibility.)

Some notes that do not fit into the flow of the general article.

You can find some background at https://archive.fosdem.org/2017/schedule/event/naturalscriptwritingguile/

That’s where it started. Though I ended up not giving the talk myself because I was ill (so cwebber took over).

Though IIRC that misses one essential motivation I have to work on it: I realized that the difference between plotting in Starcraft 1 and Starcraft 2 is that in SC1 they could tinker with the story to the very end and in SC2 their high-quality plot-videos restricted the writers from doing last minute changes.

And I think the part of the game that will be most polished in the end is the one that can be edited at any time. That’s why enter-three-witches strictly drives the game from the story and dialogues.

If you decide to port it, also have a look at the outcomes system: https://hg.sr.ht/~arnebab/dryads-wake/browse/game-helpers.w?rev=tip#L171

That allows me to analyze branching plots with a simple code walker: https://hg.sr.ht/~arnebab/dryads-wake/browse/analyze-plot.w?rev=tip#L43

It generates plot diagrams.

That shows a scene-graph and lists the outcomes I did not yet check against, so I can be sure that player choice matters, because I include a consequence for every decision players take.

Translations are by the way the biggest hurdle with the enter-three-witches syntax. There’s no good way to translate that with gettext or such. The best bet would be to treat the text as actual prose and translate it in one go.

But I actually think that that’s what should be done for game plot text, because it is (and should be) complex prose and not some menu elements that can be translated in isolation.

The syntax for Enter is about the deepest dive I took into macros. The Enter macro generates new macros for the introduced people and those macros quasiquote their arguments and then process them word by word: each word is split into letters and printed with some delay and commands like ,(something) are executed once the word gets processed. So it should work to also use them to play sound effects or trigger graphic effects exactly when some word is spoken.

, is handled by either putting it at the end of words (where it works) or by escaping it as ., – same for period (.. ⇒ .). Those are sometimes needed when you want to unset color with ,(color #f) and then add a final period.