If/then interactive stories are different and unique then those that are commonly written in the normal fashion. Users can create/influence a dramatic storyline through actions, either by issuing commands to the protagonist, or acting as a general director of events in the narrative. The narrative, and its evolution, can be influenced in real-time by a user. This is different because the viewer can choose what path they want rather than watching the suspense of the protagonist making the wrong choice, or the relief of him making the right one.
These’s a weird relationship between interactive storytelling and computer games. Much research in the community focuses on applications to computer games. There are several key issues in interactive storytelling. Number one’s how to generate stories which are both interesting and coherent; and number two’s how to allow the user to intervene in the story, without violating any rules of the genre.
Environmental approaches are those which take an interactive system, such as a computer game, and encourage the actions of a user in such a way as to form a coherent plot. Emergent behaviour forms story-like behavior regardless of the users actions.
Data-driven strategies have a library of “story components” so general that they can be combined smoothly in response to a user’s actions (or lack thereof).
Language-based approaches require that the user and system share some, very limited, domain-specific language so that they can react to each other and the system can ‘understand’ a greater proportion of the users actions.