Doom may have been released over 20 years ago, but many games are still being written with a linear narrative - one with a single timeline leading from the beginning to the end. This was largely due to cost, but Disney Research has developed a cheaper way to make nonlinear games - ones where a player's actions can affect what happens next.
Disney Research published a paper on Friday which details a new platform for developing an Interactive Behavior Tree. This is a type of graphical modeling language which enables creators to lay out multiple story arcs which split off from a linear narrative based on either in game events or the actions of the user.
Disney's researchers have developed a platform which makes it easier for creators without sophisticated programming skills to craft as many story arcs as they can think of, all of which hinge on a user's actions. The researchers also came up with a way to automatically detect and resolve narrative inconsistencies caused by unexpected actions on the part of a user.
As you can see in the following video, the augmented reality bears respond to the player's actions (putting down QR-code bearing game cards). If the game decides that the next stage of the narrative requires, for example, the beach ball which the player had removed earlier, the game will have one of the bears ask the player for a ball. Alternatively, the game might have the bears go look for the treasure chest so they can buy a ball from the toy vendor (the third bear in the video).
To be clear, the idea of building a tree of possible outcomes and story arcs is not new; a well-known recent example would be The Stanley Parable, a 2013 game which let the player either listen to the narrator's comments or ignore them and completely muck up the ending.
But the upside to Disney's platform is that it reduces the work required to write that type of complex non-linear story. "With this structure, increased user interaction does not make the author’s task more complex," said researcher Mubbasir Kapadia, "so we can now imagine ways of giving the user more freedom to interact freely with the virtual world."