Anticipatory Guidance of Plot

An anticipatory system for guiding plot development in interactive narratives is described. The executable model is a finite automaton that provides the implemented system with a lookahead. The identification of undesirable future states in the model is used to guide the player, in a transparent manner. In this way, too radical twists of the plot that lead to behaviors of the autonomous fellow players, which may be experienced as counter-intuitive, can be avoided. Since the player participates in the development of the plot, such guidance can have many forms, depending on the environment of the player, on the behavior of the other players, and on the means of player interaction. We present a top-down design method for interactive narratives which make designs suitable for the implementation of anticipatory mechanisms. Use of the method is illustrated by application to our interactive computer game Kaktus. 1 Interactive Narrative Interactive narrative is a form of entertainment that invites users to step into and interact with a fictive world. In contrast to traditional non-interactive narratives, participants in an interactive narrative are active in the creation of their own experiences. Through their actions players interact with other agents (some of which might be artificial) and artifacts in the world—an experience that can be compared to role-playing or acting. Interactive narrative promises to empower players with a greater variety of offerings but also the capacity to deal with them [22], leading to deeper and more engaging experiences. There is a fundamental conflict between interactivity and narrative. In narrative media experiences, such as suspense, comic effects or sympathy often depend on the ability to specify a sequence of events in the ‘right order’. In interactive narratives, in which the player occasionally takes control of what will happen next, such effects are difficult to achieve. A player, in a few mouse clicks, may ruin an experience that has painstakingly been designed by an author. By limiting the amount of options, a player may be pushed along an intended path, but at the same time such a design will decrease her amount of influence over the story. Stories are ultimately about characters, and hence agents have long been considered natural elements in many story-telling systems [1, 3, 8, 10, 18]. To date there has been a fair amount of research regarding various aspects of interactive narratives. However, most agent-based interactive narrative systems have adopted a locally reactive approach, where individual agents within the system ground their actions in their own perception of the current situation [15]. Comparatively little effort has gone into research on how to integrate local reactivity with a global deliberative plot control mechanism [16, 24]. Selecting what events to recount and how to order them is what makes up the plot of a story. The same basic story may be told in many different ways, depending on the order in which events are disclosed to the player. Plot control concerns itself with deciding which event of a story to present next, not to create entirely new stories (cf. [25]). The player should have the feeling that anything may happen while being nudged through the story along various story arcs [8]. At the same time the player should feel that the choices she makes has a non-trivial impact on how the plot unfolds. We will, in Section 2, present our own interactive narratives project, by means of an example. This example is then used as our object system S in an anticipatory system for guiding players through interactive plot development. The details of an automaton model and effectors of the anticipatory system are presented in Section 3. Since we present work in progress, we conclude by identifying topics for future research.