Brian Schwab - best known as the senior AI designer and gameplay engineer for Blizzard's online card game Hearthstone - left his former employer with no regrets, after working with the company for half a decade. His destination? A small, London-based team, with an extremely fascinating project under its belt.

It's an artificial intelligence-driven storytelling engine which the team hopes will serve as the next stage in the evolution of narrative games. According to them, it will eventually bring emergent narrative to games at a fraction of the current cost, equipping developers with the ability to create branching story arcs with a level of complexity more powerful than anything we've ever seen.

The engine, known as Storybricks, was first announced this year at the 2014 Game AI Conference in Vienna. There, Schwab explained that with it, his team hopes to address one of the largest elephants in the room as far as video game storytelling is concerned: the prevalence of superficial choices in modern games.

To some degree, it's a problem with how games are made. The cost of producing just a few hours of gameplay is enormous, especially in narrative titles. What this means is that the majority of story-driven games - while offering some illusion of choice - ultimately follow a narrative path that doesn't offer a great deal of replay value.

Much as I'm loathe to admit it, this includes titles like The Wolf Among Us and The Walking Dead.

"Most branches are built into the storyline and aren't really branches, they're just the storyline with certain substitutions made," explains lead designer Stephane Bura. "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."

Storybricks looks to solve this longstanding storytelling problem by changing how video game writers approach authorship. In traditional video game storytelling, explains Bura, developers try to create a game whose events unfold based on the choices the players make. In this model, the player identifies trigger conditions in the game world which 'unlock' the next step in the story based on the choices they make. Although it can open up a plethora of fascinating gaming opportunities, it's ultimately rather superficial.

Storybricks' approach has authors designing a "story economy" rather than a single narrative; one which focuses more on the characters involved than on any overarching plot-line. Using something known as an AI Director, the engine automatically creates branches where necessary through procedural content generation. This Director utilizes a series of "bricks" created by the designer which defines both character motivations and the impact that those motivations have on their surroundings.

From what I understand, there are three primary types of "Bricks:"

Drives define the needs or goals of the characters; those tasks they're motivated to pursue above all else.

define the needs or goals of the characters; those tasks they're motivated to pursue above all else. Changes to the hero include anything which modifies how the player appears to those around them. This includes fame/infamy,

to the hero include anything which modifies how the player appears to those around them. This includes fame/infamy, Parts are the constraints in a particular scenario which affect how the characters involved will interact with you - for example, responding with disgust if you walk into a diplomatic meeting completely naked; the mayor of a town may be more amenable to a player's help after his residents have been devastated by a dragon's attack.

Let's give an example of how all this stuff fits together. Note that I'm somewhat paraphrasing this piece on Polygon here.

Barry is the much-beleaguered leader of Barryton. His goal in life is to fend off the constant attacks from the neighboring city of Garryton, ultimately defeating his hated foe. To do this, he will need to defeat Garry's forces the next time they attack him, then stage a successful counterattack a short time later.

Barry's immediate goal - in service of his ultimate drive - is to make a friend who will help him protect his city. Barry forms an alliance with another leader named Larry, who supplies him with troops in exchange for grain to feed his starving citizens. Unfortunately, Garry - whose goal is to conquer Barryton - has Larry assassinate. Since Barry no longer has an ally, his new goal is to find a new ally who can protect him.

He has a number of different plots to choose from that will result in him befriending a suitable protector, and he can decide to switch allies at any time depending on what suits him.

At the same time, Barry might also be involved in a number of smaller plots. Maybe his brother was captured by bandits, who are holding him for ransom. Maybe he himself has a drinking problem, and his wife is cheating on him with a rival monarch. His traits and preferences will ultimately determine all the different plots he's involved in, as well as what his focus on any given activity will be.

For gaming, it's a completely new breed of storytelling; one which focuses not only on the player character as a protagonist but on the world around them. Whether or not the player is the hero, there still exists a living, breathing world outside of them, with other characters driving and triggering plotline. This, says Bura, is storytelling in its purest form; it's what stories are really all about: evolving relationships.

"Characters," he adds, "are stories trying to tell themselves."

Not surprisingly, Schwab has loose ties to developer Michael Mateas's 2005 experimental title Facade; which sees the player visiting friends Trip and Grace, where they discover the dark secrets of their relationship through conversation and interaction. You wouldn't be blamed for thinking this project is oddly similar to that one. It's the same basic idea - though in the case of Storybricks, Schwab hopes it will go significantly further.

Ultimately, the aim is for the Storybricks engine to be significantly easier to use than current story-building systems. It's a design principle Schwab carried over from his time at Blizzard.

""We wanted to package this for usability," he explains. "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."

Of course, the engine is nowhere near perfect. Although it seems like Storybricks will allow more narrative freedom than any other engine to date, it's unlikely that the scripting of its story sequences will be as well-written as a narrative which was planned out from the very start. Even so, it's a remarkable leap forward for video game storytelling - and one which I hope heralds more advances to come.