Simulation is a common feature in computer entertainment. However, in computer games simulation and story are often kept distinct by interleaving interactive play and cut scenes. We describe a technique for an interactive narrative system that more closely integrates simulation and storyline. The technique uses a combination of semi-autonomous character agents and high-level story direction. The storyline is decomposed into directives to character agents to achieve particular world states. Otherwise, character agents are allowed to behave autonomously. When the player's actions create inconsistency between the simulation state and storyline, the storyline is dynamically adapted and repaired to resolve any inconsistencies. Storytelling vs. SimulationSimulation has been, and continues to be, an important part of computer entertainment. Computer games such as The Sims and SimCity are simulations in the strictest sense. The initial parameters, a model of state change, and legal player moves are the forces that drive the user's experience. Real-time strategy games are simulations of combat and have been used effectively for entertainment and for military training.First-and third-person action/adventure games also rely on simulation to a lesser extent. Each mission can be considered a simulation of physics, weapon effects, opponent movements, etc. One difference between action/adventure games and other games such as The Sims or SimCity is the use of story to constrain the player's experience to a particular narrative path.The most common role of story in computer games is to provide "glue" between missions. Modern computer games consist of interleaved periods of interactive play and cut scenes -short non-interactive scenes that transition from one mission to the next, providing the player with goals and motivation for the next segment of game play. In this mode of alternating between game play and cut scenes, story elements and simulation are kept strictly separate. This is due to the trade-off between control and coherence (Riedl, Saretto, and Young 2003). On one hand, the player wants control to make decisions for the player's

Planning and execution systems have been used in a wide variety of systems to create practical and successful automation. They have been used for everything from performing scientific research on the surface of Mars to controlling enemy characters in video games to performing military air campaign planning. After reviewing past work on these various planning and execution systems, we believe that most lack one or more key components contained in another system. To enable future researchers to build more complete systems, and avoid possible serious system failure, we identify the major technical problems any implementer of such a system would have to face. In addition we cite recent solutions to each of these technical problems. We limit our focus to planning and execution for virtual worlds and the unique problems faced therein.

Simulation is a common feature in computer entertainment. However, in computer games simulation and story are often kept distinct by interleaving interactive play and cut scenes. We describe a technique for an interactive narrative system that more closely integrates simulation and storyline. The technique uses a combination of semi-autonomous character agents and high-level story direction. The storyline is decomposed into directives to character agents to achieve particular world states. Otherwise, character agents are allowed to behave autonomously. When the player’s actions create inconsistency between the simulation state and storyline, the storyline is dynamically adapted and repaired to resolve any inconsistencies.