Constraint-based Narrative Structure Design for Various Event Development and Story Flow Understanding

The story in the game induces the user s immersion in that it is an interactive storytelling. Since the interactive storytelling has a nonlinear structure unlike the existing linear structure of the story, a narrative structure different from the existing narrative structure has been studied. There are largely case-based tree-based narrative structure, constraint-based narrative structure, and character-based narrative structure. Tree-based narrative structure has developed to various algorithms such as HTN and HSP. There are disadvantages that the size of tree becomes larger as the number of branches increases and that the degree of freedom of story is lowered. In the case of character-based narrative structure, this narrative structure designs the character, not the events, and lets the character to act freely. it could be more suitable for the game because the player immerses in the character. There is a disadvantage that it is difficult to design the behavior of the character elaborately. This study redesigned the constraint - based narrative structure by presenting new tags to facilitate the understanding of the whole process of the story and various events. The newly proposed <event> tag is designed for easier understanding of the story flow, and the <plot> tag is designed to facilitate development of various events. This study applies the suggested narrative structure to “The Tortoise and the Hare“ in Aesop s fables as an example.