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Interactive Storytelling - Designing for the user
Simon Mayr

Last modified: 2011-06-08


An interactive drama offers a story world in which the user can have a real effect on the drama which they are experiencing. A linear or multi-linear story, as found in classical computer games, is clearly not an interactive drama because the idea of interactive storytelling is to allow for interaction with the structure of the narrative itself. One might argue that there are game genres like role-playing games which provide a high amount of interactivity and story variance but the point here is that in these games the player only interacts with objects and characters while following a predetermined story. The player does not interact with the narrative itself. Each time the user participates in an interactive drama they should experience a story that is essentially new.
My master thesis project is part of a larger project called IRIS, which is financed by the European Commission. IRIS stands for “Integrating Research in Interactive Storytelling” and is a joint project between 10 partners in 7 different countries. As stated on the project’s webpage, “IRIS aims at creating a virtual centre of excellence that will be able to achieve breakthroughs in the understanding of Interactive Storytelling and the development of corresponding technologies.”
The system we are working on is called IDtension. It is a playable interactive drama that produces meaningful events and allows users to deeply interact with it. It was developed by Nicolas Szilas at the University of Geneva and has been continuously improved for many years now. One of the main strengths of this system is that it offers a very high range of possible actions. IDtension is based on theories of narrative and the sequencing of dramatic actions is derived from a cognitive and emotional simulation of the user. Each character in the storyworld is represented by an autonomous agent with its own goals and values and they interact with each other’s and with the player character to achieve these goals. Furthermore there is an additional agent called the drama manager which ensures that the drama is consistent and believable.
The IDtension architecture consist of five modules namely the world of the story, the narrative logic, the sequencer, the model of the user and the theatre. The theatre is the interface with which the story is presented. The important aspect here is that the theatre is strictly separated from the rest of the architecture. This allows for many different possibilities to present the story. At the moment a simple text based user interface is used with the main purpose of testing the underlying system. While a text based interface is not necessarily a bad solutions there are many aspects of the current way of presenting the story that need improvement to enhance the user experience. The problem with most of the systems currently available is that most effort has been put into creating the storytelling architecture itself. Now that it is time to start thinking of ways how to present the story in a satisfying way for the user, it becomes evident that this separated approach leads to some significant difficulties because many of the design decision for presenting the story evidently feed back to the very basics of creating the storytelling engine.
There are many factors that influence the user experience. A first important point is the perspective from which the story is told. To really engage into the narrative it is necessary for the user to identify with the main character. The user has to have the feeling that their actions are really significant for the development of the story. As mentioned before IDtension keeps a model of the user by evaluating previous actions according to narrative criteria. Certainly there are many different users with many different personalities and it is important for interactive systems to present that stories that are most appealing to each of these different personality types.

So the main research questions are:

• How to develop relations to a character/characters/events?
• How to handle different users differently?
• How to identify emotional states?
• How to bias the user in a desired (by the author) mood?

Creating a desired mood is a key element to the success of a story and there are many different ways to create this mood in interactive drama. Some of these possibilities are the dialog system and the interaction with other characters. Since the characters in IDtension are not just some pre-programmed entities responding to the characters actions but autonomous agents with their own goals and values there is high potential for creating interesting interaction and these interactions will always be different according to the current state of the world and the previous actions of the user. Thereby new sub-stories are created depending on what the user does at what time and this creates a feeling for really being responsible for the progress of the story. This helps the system to ensure that the user keeps being interested into the storyline and has a feeling of tension and relevance of action. This is another aspect of interactive drama that sets it apart from computer games. In classical games the goal of the player is to “beat” the game and thereby be victorious. Chris Crawford made an interesting statement in his book on interactive storytelling saying “In tragedy, the reward is applause, not victory” [1, p. 216]. This means that the user should rather feel as some sort of co-author of an interesting drama than a player who beats the story.

My research focus is on the visual presentation of the interactive drama in a way to create a satisfying experience for the user. This includes the design of the user interface as well as the visual presentation of the storyworld. Furthermore I am interested in the influence of music on the user’s emotional state and therefore their decision.

Finally the evaluation of interactive storytelling is a major scientific endeavour within the IRIS Network. While technical evaluation of the system components will always remain an important step, there is also need for a methodology evaluating the overall acceptability of interactive media by end-users. This will include acceptance of the technology and an evaluation of the user experience, and even judgments about the aesthetic quality of interactive stories. These results can then be fed back to the technical designers of interactive storytelling systems.
[1] Crawford, C. (2005). Chris Crawford on Interactive Storytelling. Berkeley: New Riders.

[2] Szilas, N. (2003). IDtension: a narrative engine for Interactive Drama. In Göbelet al. (eds) Proceedings of the 1st International Conference on Technologies for Interactive Digital Storytelling and Entertainment (TIDSE) 2003. Darmstadt, Germany. IRB Verlag.

[3] Szilas, N. (2007). A Computational Model of an Intelligent Narrator for Interactive Narratives. Applied Artificial Intelligence, 21(8), 753-801