  Emergent narratives provide a unique and compelling approach to interactive
storytelling through simulation, and have applications in games, narrative
generation, and virtual agents. However the inherent complexity of simulation
makes understanding the expressive potential of emergent narratives difficult,
particularly at the design phase of development. In this paper, we present a
novel approach to emergent narrative using the narratological theory of
possible worlds and demonstrate how the design of works in such a system can be
understood through a formal means of analysis inspired by expressive range
analysis. Lastly, we propose a novel way through which content may be authored
for the emergent narrative system using a sketch-based interface.
