  Automated plot generation for games enhances the player's experience by
providing rich and immersive narrative experience that adapts to the player's
actions. Traditional approaches adopt a symbolic narrative planning method
which limits the scale and complexity of the generated plot by requiring
extensive knowledge engineering work. Recent advancements use Large Language
Models (LLMs) to drive the behavior of virtual characters, allowing plots to
emerge from interactions between characters and their environments. However,
the emergent nature of such decentralized plot generation makes it difficult
for authors to direct plot progression. We propose a novel plot creation
workflow that mediates between a writer's authorial intent and the emergent
behaviors from LLM-driven character simulation, through a novel authorial
structure called "abstract acts". The writers define high-level plot outlines
that are later transformed into concrete character action sequences via an
LLM-based narrative planning process, based on the game world state. The
process creates "living stories" that dynamically adapt to various game world
states, resulting in narratives co-created by the author, character simulation,
and player. We present StoryVerse as a proof-of-concept system to demonstrate
this plot creation workflow. We showcase the versatility of our approach with
examples in different stories and game environments.
