Interactive drama has been discussed for a number of years as a new AI-based interactive experience (Laurel 1986; Bates 1992). While there has been substantial technical progress in building believable agents (Bates, Loyall, and Reilly 1992; Blumberg 1996, Hayes-Roth, van Gent, and Huber 1996), and some technical progress in interactive plot (Weyhrauch 1997), no work has yet been completed that combines plot and character into a full-fledged dramatic experience. The game industry has been producing plot-based interactive experiences (adventure games) since the beginning of the industry, but only a few of them (such as The Last Express) begin to approach the status of interactive drama. Part of the difficulty in achieving interactive drama is due to the lack of a theoretical framework guiding the exploration of the technological and design issues surrounding interactive drama. This paper proposes a theory of interactive drama based on Aristotle's dramatic theory, but modified to address the interactivity added by player agency. This theory both provides design guidance for interactive dramatic experiences that attempt to maximize player agency (answering the question "What should I build?") and technical direction for the AI work necessary to build the system (answering the question "How should I build it?"). In addition to clarifying notions of interactive drama, the model developed in this essay also provides a general framework for analyzing player agency in any interactive experience (e.g., interactive games).
This neo-Aristotelian theory integrates Murray's (1998) proposed aesthetic categories for interactive stories and Aristotle's structural categories for drama. The theory borrows from Laurel's treatment of Aristotle in an interactive context (Laurel 1986, 1991) but extends it by situating Murray's category of agency within the model; the new model provides specific design guidelines for maximizing user agency. First, I present the definition of interactive drama motivating this theory and situate this definition with respect to other notions of interactive story. Next, I present Murray's three categories of immersion, agency, and transformation. Then, I present a model of Aristotle's categories relating them in terms of formal and material causation. Within this model, agency will be situated as two new causal chains inserted at the level of character. Finally, I use the resulting model to clarify conceptual and technical issues involved in building interactive dramatic worlds, and briefly describe a current project informed by this model.
(Source: Author's abstract on ebr)