As an alternative to the different routes between common events offered by parallel paths, non-linear narratives offer the user the chance to control the order of the stages between the beginning and the end of the experience.
Again all the content is predefined but the user can sequence the material in a manner of their choosing, rather like connecting assorted lengths of pipe. Although every viewer receives the same introduction to the narrative and, in most cases, the same ultimately successful conclusion, they choose their own route through the elements.
Each story segment has to be self-contained without any dependency on prior experiences because of the inability to know where the user is coming from but collectively the elements work like a jigsaw puzzle to present the full picture. Puzzle adventures such as Myst demonstrate this approach by offering a free roaming experience through related challenges. Only at the end, when all the pieces have been explored is the storyline fully understood and the conclusion sensible.
The random rearrangement of elements is the basis for films such as Momento and, more recently, Inception but in traditional media it is the author who determines the sequence. If they do it well, they seed each sequence with sufficient clues to simultaneously reward and tease the viewer. These gentle interdependencies help reinforce the experience. The educational thinker John Dewey identifies the educational importance of continuity by arguing that every experience takes something from previous events and modifies the perception of those that come afterwards. Most valuable experiences only “live fruitfully and creatively in subsequent experiences” he says in his book Experience and Education (p28) [summary].
The crucial aspect of this non-linear model is its ultimate need for completeness: although it doesn’t matter what order the user examines the content, for it to make sense, they have to see it all.
The whole Interactive Narrative series is: