The Problem of Internal Consistency

When people think about the challenges of interactive storytelling, this is the problem they think of most often: how to provide a consistent, well-formed story experience to the player if the player has great freedom of action? If you give the player a lot of freedom, he will have the power to subvert your story. There seems to be an inverse relationship between player freedom and story coherency.

There are three ways a player can destroy a game's story: violate the game world (by introducing things that don't belong there, often through speech); violate their own character (by acting in ways that are inconsistent with the way the avatar is defined -- in the lecture I used the example of Superman ignoring a baby crying in a burning building); and violating the plot itself, by doing something that results in an absurdity (e.g. destroying an object that reappears later in a predefined plot).

Of course, we usually prevent the player from doing these things by curtailing his freedom in various ways. Many games only offer pre-written lines of dialog, so the player can't talk about things that aren't part of the game world. Plots are designed so that the player cannot harm something that he will need later. (In the Grand Theft Auto games, you can't hurt the people who give you your missions, or even find them.) And if Superman ignores the baby, it's just a loss condition: game over.

Some designers, notably Chris Crawford and Andrew Stern, find this solution unacceptable; they feel that it is imperative to let the player do what he wants, and an interactive story must adapt to it. A few even think that we should never put a story in a video game at all, an absolutist point of view that I find ludicrous given their popularity.

The more I thought about it, the more I realized that we have constrained ourselves with some faulty and usually unstated assumptions about what interactive storytelling should be like. Here are the assumptions that we have made for years:

• "Our goal is to create a sandbox that allows maximum freedom to the player." We have believed this ever since text adventures, which gave the player the illusion that he could type in any command and the game would execute it. Of course, it never really could, but in our heart of hearts we secretly believed that someday, games would offer that much power. Another name for this is the "go-anywhere-and-do-anything" ideal.
  
  This assumption, glorious fantasy though it is, is not only unrealistic but unnecessary. The protagonists of conventional fiction are not gods; dramatic tension arises from the conflict between their need to accomplish something and the obstacles or limitations that prevent them from doing it. Nor is conventional fiction about the protagonist doing anything he feels like; it would make no sense for James Bond to give up spying and become a chef. Or, as Michael Mateas put it, "Why do I have to give the player verbs that are completely unrelated to the dramatic context? ... In 'traditional' games the player has a limited set of verbs available as well." The degree of freedom and agency that an interactive storytelling experience offers should be a function of the designer's original premise for the experience, rather than based upon an unreasonable assumption that the designer should always maximize them.

• "Interactive stories shouldn't be games," by which I mean that the player shouldn't necessarily try to "win" at something in an interactive story, because that doesn't feel storylike; nor should an interactive story include a lot of numerical mechanics. The assumption is that experiencing a true interactive story -- whatever that is -- won't feel like playing a game, or involve striving to optimize some value.
  
  I realized how limiting this is when I heard Ken Perlin propose that an interactive story could use mechanics to preserve its own believability. Perlin said, "The cost of an event in an interactive story should be directly proportional to its improbability," which I later dubbed "Ken Perlin's Law." You could give the player a wide range of actions, but the more unbelievable the action, the more it costs; do it too often and the action becomes unavailable. I called the account that the player actions should be charged against the story's credibility budget.

• "The player shouldn't have to think about any rules." Thinking about rules, and obeying them, is a game-like activity that destroys narrative immersion. We have long assumed that the ideal interactive story won't have any explicit rules and the player won't have to voluntarily constrain his own behavior. The game will respond appropriately no matter what the player tries to do.
  
  This assumption is OK for the laws of physics or economics, but it's trickier when we enter the social and above all the dramatic domains. We can use the game's mechanics to limit the player to what is possible in a physical sense, and we can construct the user interface in such a way that the player can only execute physical actions that we approve of. But if we want players to interact socially with other characters, we have to give the players the power to speak (or type), and that means they have to think about what would make sense to say. Players are already used to thinking about and obeying rules in MMOGs; if you harass another player, you get kicked out.

• "The designer is completely responsible for the player's experience." This assumption is a natural outgrowth of our expectations about books and movies: the author is in charge, and if the audience doesn't like the author's material, the author has only herself to blame. For the most part, we think the same thing about video game designers. They designed the game, so anything that goes wrong with it is their fault.
  
  But if you bring this viewpoint over to interactive stories, it means that the designer has to guarantee a well-formed story to any player who wants one, regardless of what the player does. That's a lot to ask -- too much, in fact.

Once you abandon these assumptions -- which, as I said, are deeply rooted but largely unstated -- then interesting things start to happen. Over the years, various commentators have asserted that the designer and the player collaborate to create the player's experience, but they've seldom explained what this really means. In 2006 I suddenly realized that this collaboration arises out of the player's role in the game, and particularly how that role is defined. Role-playing is the fulcrum of the balance between story consistency and player freedom. Not role-playing in the CRPG sense -- leveling up and buying weapons -- but role-playing in the dramatic sense.

When a player starts to play a game in which he enacts an avatar character, he agrees to play the role that goes with the character. It's up to the designer to decide how strictly that role is defined. Superman, for example, has no moral freedom at all; a player who wishes to enact Superman signs up to Superman's moral constraints.

MMORPGs, on the other hand, frequently allow the player to build the avatar character from the ground up, and to enact a very wide variety of roles -- one of which might be to just hang around the entrance and give advice to newbies, if that's what they want to do.

However the role is defined, when the player chooses to play, he enters into a contract with the designer. The contract is very simple, and these are its terms: The designer promises to provide a credible, coherent story if and only if the player promises to behave in credible, coherent ways.

To put it another way, with freedom comes responsibility. The more power the player has within the game world to contribute actions to a story, the more responsibility he must take for those actions.

This abandons the assumption that the player shouldn't have to think about any rules; he has to think about the rules of drama. It also abandons the assumption that the designer is responsible for everything. If the player intentionally does something to screw up the game's story, then he, not the designer, is the one at fault.

(If he screws up the story unintentionally, that's a different issue. That's the designer's fault. It's up to the designer to construct a world in which the player cannot accidentally violate the story.)

In summary, I concluded that we still have the eternal trade-off between player freedom and story consistency, but it isn't such a big problem after all. It only seemed like a big problem because we assumed that we designers had total responsibility for anything that happened; that the player should be allowed to do whatever he liked and the story should respond appropriately; and that we were required to offer him maximum freedom at all times. By making those assumptions, we set ourselves up to fail. Instead, we need to embrace the trade-off and learn to work with it. The more power that we designers keep for ourselves, the more we are responsible for the quality of the story; the more power that we share with the player, the more the player shares in our responsibility.