Dynamic emphatical narration for reduced authorial burden and increased user freedom in interactive storytelling.

Interactive storytelling systems have become very popular as they engage users in the creation of narrative. A fundamental challenge for such systems is that the users feel unconstrained in their exploration of the environment and yet retain for the author some control of what the user does. Traditional solutions address this challenge by hardening the authoring task, since much effort has to be devoted to create the story and the necessary mechanisms to provide the user with enough freedom that, at the same time, keeps the story consistent. We propose a solution based on dynamic narration that combines a set of authored materials associated with particular points in the environment and the exploratory movements of the user, and includes statements of varying emphasis to guide the user towards the desired elements. This allows the system to generate a narration in real time while giving the user the possibility to decide what to do. The solution has been field tested and results are reported on three different aspects: the freedom of the user in terms of combinations in which the authored material is traversed; the divergence of user explorations from author's intentions; and user response to guidance statements of differing emphasis.