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June 30, 2008

A Conversation with a Work of Art

Simulating true conversations in a computer game is tough stuff. We're still some way away from effectively applying computational linguistics to game playing in a way that allows a wide range of natural language input, and I'm not even sure that's an entirely desirable goal given the enormous complexity that this would introduce into game design. So for now the general approach is to restrict the range and format of player input using a system that is easily interpreted and applied, such as a "click to talk" or multiple choice dialogue tree system.

The question, however, is this: when you play a game that implements conversation, do you feel that playing through the conversation contributes in any way to gameplay? Or does the conversation feel like more of an afterthought that requires little attention or skill on the part of the player (or the developer, for that matter)?

The answer, I think, largely has to do with the goal of conversation in the game. It can be a method of providing character or game backstory, or maybe a break in the action to advance the storyline. It is also used to present the player with a choice, such as a side quest or a broad game pathway. But more often than not, the conversation is brief and shallow, without requiring a great deal of thought from the player, and without considerable effort put into things like conversation flow, structure, or context. For the most part, given the limited role of conversation in the game, these things are unnecessary and not worth the added developmental effort.

Conversation doesn't have to be limited to these kinds of functions, however. In many interactive fiction games, conversation takes on a much larger role: it directs the narrative; it offers challenges to the player; it contributes to deeper character development -- within player and non-player characters and between them. Conversation might not be nearly as much fun as actions requiring fast-twitch hand-eye coordination which are rewarded with explosions and rag-doll physics, but I have to believe that there are some methods and mechanics in IF games that could translate to non-IF games to enhance the experience, so why not conversation?

I think any discussion of conversation in games, using IF as a foundation, would have to start with Emily Short's Galatea. Of all the IF games of the past decade or so, Galatea is, I would guess, the one most played by people who would not identify themselves as IF players, perhaps because of its visibility and renown. But interestingly, it is also one of the only games I know that consists entirely of a conversation, one that takes place between the player and the one non-player character in a single room.

It's a deceptively simple construct for a game which does an excellent job of hiding the sophisticated mechanics underneath.

Galatea primarily uses the traditional ASK/TELL system for conversation with the NPC, although the majority of the time is spent ASKing rather than TELLing. Because ASK HER ABOUT and TELL HER ABOUT can be shortened to A and T, respectively, most of the player's efforts are essentially thinking up and entering topic words to discuss. Other occasional interactions are allowed, such as HELLO and GOODBYE, which are interesting inclusions; while they do help newer players get started into the game, they also represent direct statements to the NPC (as opposed to commands for the player-character), which might throw off some players into expecting other direct statements to work. Nevertheless, the basics of the ASK/TELL system are familiar to most current IF players and are not difficult, I expect, for newer players to pick up, which is one reason why I think this game succeeds in attracting a broad audience.

Still, if the game consisted only of the basic ASK/TELL system, even with its impressive range of topics to discuss, it would likely fail to keep players interested for long.

Where Galatea succeeds is in Short's dogged attention to the underlying mechanics of the conversation. The NPC in this case is not your typical information vending machine which spits out its one preprogrammed response to each topic. Here Short has taken into account things like mood, flow, and context, such that the same question about one particular topic has a different effect and response depending on the current established relationship with the NPC, what questions were just asked immediately prior, and what topics had already been discussed to that point. It's a mechanic that sounds entirely logical to a normal conversation but one that is rarely attempted in games, probably due to the complexity of design.

But does creating complexity of conversation such as this really come across as far more daunting a task than the prospect of creating hyper-realistic graphics and physics systems?

As a very simple example, in the game you note that the NPC--a statue that has become animated--moves as though she is breathing. If you ask her about her breathing, she will tell you that she taught herself to breathe, and although not necessary she does so because it is soothing. Later on, if you then ask her about sleeping, the question (not the answer, but the question from your player character) is then worded: "And do you have to sleep? Or did you teach yourself, the way you taught yourself to breathe?" But if you hadn't previously asked about breathing, the question is worded only: "So do you sleep?"

The effect on the narrative, in this case, is quite minor. But there is an elegance to it, a quality that makes the conversational narrative flow more smoothly and naturally and that shows that the game isn't merely spitting out canned text but rather is constructing context-sensitive and appropriate responses that give the impression that the game is reacting dynamically to what the player is doing and has done.

The mechanics, of course, extend far beyond decorative adaptations.

In her essay on conversation systems in IF, Short describes Galatea's system as "topic quips with mood tracking and quip-tagging," where quips are the actual snippets of dialogue used in the game. So here we have single topic quips like with most ASK/TELL systems (one predetermined player character snippet for each ASK or TELL command, instead of multiple-choice options), but she includes quip-tagging, so that once quips are used they are not repeated. In addition, some quips can be used only after other quips; in fact, the same command (e.g., ASK HER ABOUT THE ARTIST) can produce different player quips and NPC responses depending on what other topics had been discussed previously.

Mood tracking is also fascinating, in that the mood of the NPC is tracked and changes in response to certain questions and answers, which can then impact responses to subsequent questions later on. The NPC's mood is also reflected in different ways, including gestures, expressions, and tones of voice, and the system was apparently designed to accomodate these dynamically into the text of the response.

There are, of course, some limitations of this type of conversation system. As mentioned in a previous blog, the ASK/TELL topic quip system can be frustrating at times, because the player is only allowed to specify the topic of discussion rather than the specific aspect of the topic to discuss; ASK HER ABOUT THE ARTIST is an extremely broad command that could result in asking her what the artist's name is, what he looks like, or what her relationship with him is like. Generally, Galatea does a nice job keeping the questions within the current context, but there remains a degree of helplessness on the part of the player.

Another limitation is that conversations with this type of system are notoriously one-sided; the NPC in Galatea is almost entirely reactive, rather than active. This makes the resulting conversation seem only like an interview, with the player asking one question after another, but therein lies one of the difficulties of designing a conversation with a system that uses topic quips rather than multiple-choice dialogue trees: how can we easily allow the player to answer questions, in addition to asking them?

Nevertheless, this game is a notable achievement that allows players to have a conversation with an NPC that reads like, and has the feel of, a very dynamic, responsive interaction with a character that is far more three-dimensional than any character from a mainstream game. The amount of effort that Short must have put into this is frightening, although since the source code was never released, most of this is based on interpretations and assumptions in addition to her writings. Still, with all of the effort and money already put into various complicated aspects of mainstream, AAA-quality games these days, I have to wonder: what might a team of Shorts create with a AAA engine, a fistful of investment capital, and a couple years worth of effort, just by utilizing some of the basic mechanics that already exist in games like Galatea?

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