Andrew Stern

Towards Integrating Plot and Character for Interactive Drama

The authors are currently engaged in a three year collaboration to build an interactive story world integrating believable agents and interactive plot. This paper provides a brief description of the project goals and design requirements, discusses the problem of autonomy in the context of story-based believable agents, and describes an architecture that uses the dramatic beat as a s tructural principle to integrate plot and character.

Believable agents and intelligent story adaptation for interactive storytelling

Interactive Narrative is an approach to interactive entertainment that enables the player to make decisions that directly affect the direction and/or outcome of the narrative experience being delivered by the computer system. Interactive narrative requires two seemingly conflicting requirements: coherent narrative and user agency. We present an interactive narrative system that uses a combination of narrative control and autonomous believable character agents to augment a story world simulation in which the user has a high degree of agency with narrative plot control. A drama manager called the Automated Story Director gives plot-based guidance to believable agents. The believable agents are endowed with the autonomy necessary to carry out directives in the most believable fashion possible. Agents also handle interaction with the user. When the user performs actions that change the world in such a way that the Automated Story Director can no longer drive the intended narrative forward, it is able to adapt the plot to incorporate the users changes and still achieve dramatic goals.

Natural Language Understanding in Façade: Surface-Text Processing

Facade is a real-time, first-person dramatic world in which the player, visiting the married couple Grace and Trip at their apartment, quickly becomes entangled in the high-conflict dissolution of their marriage. The Facade interactive drama integrates real-time, autonomous believable agents, drama management for coordinating plot-level interactivity, and broad, shallow support for natural language understanding and discourse management. In previous papers, we have described the motivation for Facade’s interaction design and architecture [13, 14], described ABL, our believable agent language [9, 12], and presented overviews of the entire architecture [10, 11]. In this paper we focus on Facade’s natural language processing (NLP) system, specifically the understanding (NLU) portion that extracts discourse acts from player-typed surface text.

A Behavior Language: Joint Action and Behavioral Idioms

This chapter presents ABL (A Behavior Language, pronounced “able”), a language specifically designed to support the creation of life-like computer characters (believable agents). Concurrent with our development of ABL, we are using the language to implement the believable agent layer of our interactive drama project, Facade. With code examples and case studies we describe the primary features of ABL, including sequential and parallel behaviors, joint goals and behaviors for multi-agent coordination, and reflective programming (meta-behaviors). Specific idioms are detailed for using ABL to author story-based believable agents that can maintain reactive, moment-by-moment believability while simultaneously performing in tightly coordinated, long-term dramatic sequences.

Failing believably: toward drama management with autonomous actors in interactive narratives

Interactive Narrative is an approach to interactive entertainment that enables the player to make decisions that directly affect the direction and/or outcome of the narrative experience being delivered by the computer system. One common interactive narrative technique is to use a drama manager to achieve a specific narrative experience. To achieve character believability, autonomous character agents can be used in conjunction with drama management. In this paper, we describe the problem of failing believably in which character believability and drama management come into conflict and character agents must intelligently produce behaviors that explain away schizophrenic behavior. We describe technologies for implementing semi-autonomous believable agents that can fail believably.

Façade : architecture and authorial idioms for believable agents in interactive drama

Facade is a first person, real-time interactive drama that integrates autonomous characters, an interactive plot that goes beyond simple story graphs, and natural language understanding, into a first-person, real-time interactive drama experience. Since its release in July 2005 as freeware, Facade has been downloaded over 350,000 times and received widespread critical acclaim among players, game developers and mainstream press.