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Hearthstone dev invents stories that tell themselves

Brian Schwab is a former Blizzard employee best known for his work as senior AI and gameplay engineer on Hearthstone, but now he has moved on to experimental territory, he tells us. After working at the gaming behemoth for half a decade, Schwab has since joined a small London-based team to develop what they hope is the next step in the evolution of narrative games.

The result, they tell us, could bring emergent narratives to games at a fraction of the cost required to make the next Walking Dead release.

How to force Storytelling to evolve

It's called Storybricks, the team tells Polygon: It's an AI storytelling engine that gives developers the ability to create and control narratives with highly complex branching story arcs. First announced at this year's Game AI Conference 2014 in Vienna, the engine, they hope, will offer new and practical solutions to some of the long-standing problems of designing interactive stories.

And that comes down to two of the biggest elephants in the room: the prevalence of superficial choices in games, and the cost of developing them. The cost of producing a single hour of gameplay is enormous, Schwab tells us, and further branching possibilities only add to that. As a result, most narrative games the likes of BioShock Infinite and The Walking Dead follow a narrative path that offers little in the way of replayability.

"Most branches are built into the storyline and aren't really branches, they're just the storyline with certain substitutions made," say Stephane Bura, lead designer on the project. "Essentially they are completely cosmetic branches. With games that do allow for real choices, they typically are minimal, with two to three real choices that differentiate the stories, and the game is much shorter since there ends up just being that much more authored content."

So how does Storybricks work? It's a matter of changing how designers perceive authorship.

Traditional Storytelling in Games

mass effect 2

Decision tree diagram for the ending of Mass Effect 2 via Bradley Fest

Traditional video game storytelling works like this, says Bura: Developers try to create a story that unfolds based on the actions that players make. In this model, players in the game change the world by identifying trigger conditions that show the next step in the story.

But Storybrick approaches things differently.

Instead of authoring a single story, designers author a "story economy," the behind-the-scenes system of generating stories. What does this mean? Storybricks uses procedural content generation to automatically create branches where they are needed by using what the team refer to as an "AI Director." For the game designer, this is done by creating a series of "bricks" that will define the motivations of characters and the effect of those motivations on the world, and generate a new plotline on the fly based on how the player's choices influence the motivations of others.

These "Bricks" are essentially just a visual tool used to describe some of the more technical concepts in the engine. The most important are "Drives" which define the needs or goals of in-game characters. Next are "Changes" to the hero like an increase in fame after finishing a quest, and then "Parts" which refer to constraints of a scenario that define how other characters will interact with you such as low health.

Because of how Storybricks focuses on character "drives," evolving narratives originate from storylines in which players are not the protagonist. There is a world outside of yours character and it's the drives of that world's other characters that triggers these plots. This is what stories are about, says Bura: evolving relationships.

An Example

  • Ted is the King of Tedville. His goal in life is to conquer nearby Bobland. Conquering Bobland requires at least one ally and winning three major city battles
  • Ted has Tom for a friend, and they're taking over city 2. Tom dies (or even stops being Ted's friend for whatever reason). Ted can no longer forward this plot. His new goal is to get another friend, in order to fill the requirements of his larger plot
  • He chooses from a number of plots that would result in him befriending somebody suitable as a conquering buddy, and completes that plot. Alternatively he can change allies in the middle of the campaign, then he can start back up on city 2, otherwise he might have to retake city 1
  • At the same time he could also be involved in several smaller plots that involve totally different story elements. Maybe he has a drunk brother that he needs to deal with. Maybe he has a cheating wife. Maybe he just got invaded by some other King himself. The sum total of what he's involved in, as well as what he's prioritizing at any given time, is fully determined by his traits and preferences, as well as how much of his focus any given plot activity is taking up

In this sense, characters and plots are built in the same way. "Characters," says Bura, "are stories trying to tell themselves."

This might all sound familiar to those who have keenly followed the evolution of "AI Directors" in games. In 2005, developer Michael Mateas led a similar experiment into interactive fiction with the release of the artificial intelligence game Facade. In Facade, players are invited to the home of a couple and by engaging with them through a series of conversations begin to learn darker secrets of their relationship.


Schwab has loose ties to Mateas' earlier project, as he currently an advisor to the designer. But while Facade's storytelling AI was evidence of the stories that can be told through interaction, Schwab hopes Storybricks will go much further.

The aim of Storybricks is for the engine to be easier to use than current story-building systems  something that Schwab relates to the game design philosophy seen in his earlier career at Blizzard. "We wanted to package this for usability," Schwab says. "It's like what Blizzard have been doing: It's about package and polish. You take a very sophisticated tool and make it a toy."

AI Directors continue to be of interest throughout games development despite a severe lack of attempts to make them. BioShock honcho Ken Levine has spoken openly about his interest in the Storybricks engine in relation to his approach to narratives earlier in the year during GDC 2014, while Heavy Rain's David Cage has similarly predicted a future of algorithms in charge of narrative design.

While more work is still necessary to perfect the system, the team tells us the hardest part  branching has been solved.

The next level of puzzles.

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