Michael Mateas
Dept. of Computer Science, Carnegie Mellon University  
michaelm@cs.cmu.edu  

Andrew Stern
Independent Artist and Researcher
http://www.interactivestory.net
andrew@interactivestory.net

Interactive drama concerns itself with building dramatically interesting virtual worlds inhabited by computer-controlled characters, within which the user (hereafter referred to as the player) experiences a story from a first person perspective (Bates 1992).  Over the past decade there has been a fair amount of research into believable agents, that is, autonomous characters exhibiting rich personalities, emotions, and social interactions (Bates, Loyall and Reilly 1992; Blumberg 1996; Hayes-Roth, van Gent and Huber 1997; Lester and Stone 1997; Mateas 1999; Stern, Frank, and Resner 1998). There has been comparatively little work, however, exploring how the reactive behavior of believable agents can be integrated with the more deliberative nature of a story plot, so as to build interactive, dramatic worlds (Weyhrauch 1997; Blumberg and Galyean 1995).  Likewise, the computer game industry has had little success in creating powerful interactive narrative experiences in their games. Virtually all of today's computer games focus on some sort of action-oriented, strategy-oriented or puzzle-oriented interactivity as the core of the experience.  Some incorporate a story-line to accompany the game, but these stories are mostly linear and unchangeable, often serving as a justification to solve yet another puzzle or fight another opponent.  Players have little or no control over the course of the narrative, and AI plays little or no role in developing the narrative (Stern 1999; Mateas 1999a; Stern 1998).  Games often have characters in them, such as in adventure or role-playing games, but with few exceptions they are not "believable", behaving one-dimensionally and predictably, with little potential for more than shallow interactivity.  Perhaps most fundamentally, the intention of today's computer game is to play a game, with story holding a secondary, supportive role at best.

Motivated by their belief that a "fully-realized" computer-based interactive drama has not yet been built, the authors are currently engaged in a three year collaboration to build Façade, an interactive story integrating an interdisciplinary set of artistic practices and artificial intelligence technologies.  Together they will:

- create a compelling, well-written story that obeys dramatic principles, designed with many potential ways to play out
- build artificial intelligence (AI) that can control the behavior of realtime-animated computer characters, to be used for performing the roles of all but one of the characters in the story;
- create a user interface that allows the player to easily move within the world, and converse and gesture with the computer characters;
-  build AI that can understand natural language and gestural input within the context of the story;
- build AI that can integrate the user's interactions into the space of potential plot directions and character behaviors in the story;
- collaborate with voice actors and animators to author spoken dialogue, character behavior and story events within the engine, to construct the finished story world.

The talk will provide a description of the story requirements grounding the design of this particular interactive story, a description of the use of traditional dramatic structure to inform the design of both the system architecture and the player experience, and an apologist defense of the use of traditional dramatic structure in an interactive context.