Emotional Mechanics

[Most months, I devote the second Tuesday of the month to a mailbag post that answers a question someone’s sent to me. I’m still doing one of those in March, but it will come out in two weeks’ time.

Instead, this post is part of a short series on Character Engine and what we’re doing at Spirit AI. I’m writing these posts with IF and interactive narrative folks in mind, but more general-audience versions of the same content are also appearing on Spirit’s Medium account. Follow us there if you’re interested in hearing regularly about what Spirit is up to.]


In January, I published a talk about conversation as gameplay, and in particular my ECTOCOMP game jam piece Restless. There, I talked about using Character Engine to give the player more expressive ability. They can tune their dialogue to be open, scary, vulnerable, aggressive, playful; they can pick input topics that they want to focus on.

I’m now revisiting Restless to address some of the flaws I identified in that piece, to give it a better tutorial introduction, polish its use of dynamic text, and add some depth to the content. Tea-Powered has created some additional art, so we can better signal gradations of character emotion. And I’m also refining some of the mechanics under the hood, particularly those that deal with gradual changes in character emotion.

What I’m going for in terms of the design:

  • perceivable consequence:
    • all of the player’s actions should have some effect on the outcome of the story, even if just by moving stats in one direction or another
    • the NPC’s emotional state should be apparent to the player, communicated through art, words, and actions
    • some areas of the NPC’s emotional state space should trigger narrative progression, by having the character get angry, leave, reveal new information, go back to sleep, etc
  • intentionality:
    • the NPC’s reactions should be consistent and predictable enough that the player can choose what to do and be rewarded by an expected outcome, even if there is an additional unexpected consequence
    • the player should have some warning when the NPC is approaching a state that will trigger a significant reaction
  • hysteresis:
    • the NPC should not rapidly cycle back and forth between two emotional states in response to opposed actions from the player; the history of interactions should matter
  • varied narrative intensity and pacing
    • not all player actions should be of equivalent efficacy; some actions should be more important, memorable, or high-stakes
    • it should not be possible to achieve an important result by grinding repetition of an unimportant action

That last point possibly deserves a little bit of expansion. One of the issues with stat-based relationship tracking in games is that it can mean that you could do a lot of banal minor services for a character, and work your way to a point where you’ve maxed out your affinity and now they want to marry you.

This is bad for multiple reasons. One, it’s unrealistic; humans don’t work like that. Two, it’s boring gameplay and boring story. Doing minor favors over and over feels like a chore, from a gameplay perspective. And narratively, there’s no sense of rising stakes, or risk, or the thrill of the relationship becoming more intense.

One way to resolve this would be to throw away the consequences of player action after a certain point. If you’re already at 50% affinity, paying one more compliment to the character does nothing at all. Now you can’t grind your way to romance through compliments: problem solved! Except that this goes against the earlier design principle that all player actions should have consequences of some kind.

So, instead, what we have to do is turn off the player’s ability to do minor actions when we’re in major consequence territory. Compliment away… while your relationship is still in trivial flirt zone. But work your way up to where things are getting serious, and the available affinity moves also get more serious, more freighted. And just having those “bigger” moves popping up in the choice menu should communicate to the player, along with the character art, that we’re in a more important situation.

Fortunately, all of that is pretty doable, by restricting dialogue lines to particular ranges of the emotional space.

This work is still in progress — I’ll post when the new version of Restless is generally available.

Natural Language Understanding for Characters

[This post is part of a short series on Character Engine and what we’re doing at Spirit AI. I’m writing these posts with IF and interactive narrative folks in mind, but more general-audience versions of the same content are also appearing on Spirit’s Medium account. Follow us there if you’re interested in hearing regularly about what Spirit is up to.]

Character Engine is designed for two kinds of interaction: it can either generate input options for the player (as seen in Restless), or it can take natural language input, where the user is typing or using a speech-to-text system.

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That natural language approach becomes useful for games in AR or VR where more conventional controls would really get in the way. It’s also good for games that are using a chatbot style of interaction, as though you were chatting to a friend on Facebook; and a lot of interactive audio projects deployed on platforms like Alexa use spoken input.

There are plenty of business applications for natural language understanding, and a lot of the big tech players — IBM, Google, Amazon, Microsoft, Facebook — offer some sort of API that will take a sentence or two of user input (like “book a plane to Geneva on March 1”) and return a breakdown of recognized intents (like “book air travel”) and entities (“March 1”, “Geneva”). If you prefer an open source approach over going to one of those companies, RASA is worth a look.

For people who are used to parser interactive fiction, there’s some conceptual overlap with how you might set up parsing for an action: we’re still essentially identifying what the command might be and which in-scope nouns plug into that system. In contrast with a parser, though, these systems typically use machine learning and pre-trained language models to allow them to guess what the user means, rather than requiring the user to say exactly the right string of words. There are trade-offs to this. Parsers are frustrating for a lot of users. Intent recognition systems sometimes produce unexpected answers if they think they’ve understood the player, but really haven’t. In both cases, there’s an art to refining the system to make it as friendly as it can be, detect and guide the user when they say something that doesn’t make sense, and so on.

Some natural language services also let the developer design entire dialogue flows to collect information from the user and feed it into responses — usually interchanges of a few tens of sentences, designed to serve a repetitive, predictable transaction, and lighten the load on human customer service agents.

Those approaches can struggle a bit more when it comes to building a character who is part of an ongoing story, who has a developing relationship with the player or user, and who uses vocabulary differently each time.

That’s exactly where Character Engine can naturally provide a bit more support. We’re tracking character knowledge and personality traits. We’re doing text generation to build output that varies both randomly and in response to lots of details of the simulated world. And because dialogue in Character Engine is expressed in terms of scenes of interaction, making it easier to maintain large and complex flows where the same input should be understood differently at different times.

We don’t want to be in a race with the providers of existing NLU solutions, though. What we want to do is facilitate author-friendly, narrative-rich writing options that tie into whatever happens to be the current state of the art in language understanding. So here’s a bit about how we do that:

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Memory and Knowledge for Characters

[For a couple of years now, I’ve reserved the first Tuesday of the month for a review of a book on writing or game design that might be of interest to IF folks. I’m still doing one of those in March, but it will come out the 19th, while I’m at GDC.

Instead, this post is part of a short series on Character Engine and what we’re doing at Spirit AI. I’m writing these posts with IF and interactive narrative folks in mind, but more general-audience versions of the same content are also appearing on Spirit’s Medium account. Follow us there if you’re interested in hearing regularly about what Spirit is up to.]

Knowledge and memory are a somewhat vexed area for game characters. It’s easy to think of characters who don’t remember the last fifty times you asked them the same exact lore question, or are strangely forgetful about the ways you’ve harmed them, or who aren’t equipped to answer common-sense questions about the world they live in.

So why is this a problem? Simply recalling that something has happened is not the main challenge. We can set flags; we can assign variables; we can check on quest journals to see what the player has already done. We can refer back to whatever data store is otherwise tracking world state in this game.

The hard part is building a system where

  • everything important to remember is stored in a reasonably systematic way
  • differences between world truth and character knowledge are handled as much as (and no more than) useful
  • there’s a way to track and author for the combinations of possible state so that the NPCs always have something to say about what they remember and know

There are quite a few technical, design, and writing challenges packed into those three bullet points.

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Conversation as Gameplay (Talk)

[Yesterday I gave a talk at the Oxford/London IF Meetup. The session was about conversation as gameplay, and also featured Flo Minuzzi of Tea-Powered Games, speaking about their released game Dialogue and their upcoming Elemental Flow. There’s a nice livetweeted thread version of my talk available on Twitter thanks to Florence Smith Nicholls, but I promised also to make a blog post about what I said.

Because the talk was written for an audience that included students, game designers from other parts of the industry, and newcomers to interactive fiction, I included some history of my own work that may be redundant for readers of this blog; there’s also some overlap with a talk I gave in Warsaw last September. However, the material towards the end of this talk is largely new.]


The Problem Statement

I want more games to be about human interaction, about the nuances of how people deal with one another, about the kinds of topics that appear in dramatic movies. That’s partly because I’d like to play more games about conversation and social interaction. I’m not as interested in action as a topic, and to be honest I often fall asleep during superhero movies these days.

Meanwhile, as an artist, part of the reason I write games is to explore and interrogate things I don’t yet fully understand. Building procedural systems and seeing how they perform is a great way to explore whether our mental models are correct. How people understand each other (or don’t), how they connect and why, are topics of enduring fascination for me.

So I want more conversation-rich games. For that to work as I’d like, the conversation needs to be rewarding as gameplay — not just bolted on around gameplay, as it so often is.

When it comes to my own work, I have a few more ambitions and requirements as well:

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First, I want it to allow the player to act with intentionality: to lay plans and carry them out. That means that we need some systematic mechanics that the player can learn and manipulate.

For the purposes of this talk, I’m not spending much time on things that are pure branching dialogue trees without ongoing state or clear mechanics. I’ve sometimes written work in that space, and if you’re interested in how to get the most out of a relatively state-light dialogue presentation, I recommend having a look at Jon Ingold’s AdventureX talk about writing sparkling interactive dialogue. But that’s not what we’re looking at today.

[I’ve written more about world model and systematic mechanics for conversation elsewhere.]

Second, I want the resulting mechanic to have good pacing and dramatic qualities — so a mechanic that systematizes conversation but makes it feel very slow, stilted, metaphorical, or hard to manipulate is not what I’m looking for. Some of these can be cool to play, but I myself tend to be looking to write something that has a bit more fluidity.

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So I released a new game! Here’s its blurb:

You’ve been haunting old Mrs Fagles for decades. Now she’s sold the house, and the new owner’s moved in. Sylvie’s broke, bad at plumbing, and anxious about everything.  And with a living, breathing, fretting roommate, how are you supposed to rest in peace?

Drink blood. Set fires. Tell lies. Give advice, loan out a wedding dress, reclaim your true name.  Remix your dialogue options to reflect your mood or dig deeper into the topics that interest you.

I mentioned this briefly in yesterday’s link round up, but I wanted to give a little more background on it than a link round up typically allows for.

Restless is a game written for ECTOCOMP, a venerable Halloween-themed IF competition. There are six endings, if you’re counting — though some of those endings mean different things depending on how you get to them.

It’s a purely conversation game. As in a lot of choice-based games, you have up to three options, and you can pick one. But in contrast to the typical dialogue situation, you can do something about it if you don’t like your current menu. Click a mood, and your options will shift to reflect that new attitude. Turn on moods individually or in combinations. Discover conversation topics and you can set your dialogue to explore those too.

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The Red Strings Club (Deconstructeam) and Minigame Conversation

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The Red Strings Club is a cyberpunk narrative experience about fate and happiness featuring the extensive use of pottery, bartending and impersonating people on the phone to take down a corporate conspiracy.

The Red Strings Club was recommended to me by a reader who explained that this was a game that used mixology as its conversation interface. If you want someone to talk to you, you make them a cocktail.

That does really sound like my kind of thing, I have to admit. I have written multiple prototype games, all of them sadly occupying dusty corners of my hard drive, that were based on some variation of “you have to mix evocatively-described liquids together in order to elicit information.” In one, it was a form of scrying with magical ingredients. In another, you were going to custom mix perfumes for yourself to wear to social events in order to subtly influence the conversation of the nobles around you. In a third, your choice of how to weight components in the mixture was going to drive the probabilities in generated descriptive text, so if you used a lot of one liquid you might become more perceptive about physical qualities, or a lot of another liquid would reveal memories.

None of these projects ever got finished. The perfumes one didn’t get further than an “oh I think I see how I’d do that” level of spec. But what appealed to me was a combination of challenge, physicality, and expressiveness

The challenge would have to do with the mixing rules: you might find that the ideal potion to scry out the murderer was one requiring ingredients that reacted horribly together, and you’d need to find a way to mix them safely.

The expressiveness would arise from the fact that you’re combining several elements into a single choice, and they could carry different axes of information. Imagine a perfume in which the top and heart notes express the noun and verb of action, the “what are you doing” portion of the command, while the base note expresses how you feel about it, a touch of protagonist characterization. Patchouli for the earnest, unguarded, irony-free. Sandalwood if you’re old enough to know better but not quite old enough to be genuinely subtle. Myrrh for bitterness. Vetiver for an inscrutable smirk.

It’s too rare in games that we’re allowed to say whether we take an action eagerly, or joyfully, or with reservations, or because we can think of no alternative.

Anyway. That is a very long preamble to say: that is not how The Red Strings Club works at all.

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