Jason Hutchens AI Team Lead – Team Bondi
Interactive Drama Dynamic Dialogue and Sandbox Worlds
ABOUT ME • Research in Grammatical Inference and Data Compression. • Worked at Lionhead Studios on Black & White. • Former “Chief Scientist” of Artificial Intelligence Inc. in Israel. • Recently joined Team Bondi as AI Team Lead.
SCOPE • No State Machines, Scripting, A* or Flocking. • Use AI to create a dramatic experience for the player. • What can be achieved on Sony's next-gen console?
ARTIFICIAL INTELLIGENCE • A contentious term. Slippery to define • Turing un-asked the question “what is intelligence” via his Test. • We're specifically interested in behaviour that appears intelligent.
INFORMATION THEORY • Intelligent behaviour is unpredictable yet relevant. • Eliminate randomness and repetition – maintain reasonable surprise. • Behaviourism predicts the “slot machine” phenomenon.
EXAMPLE • Stochastic language models generate unpredictable sentences: MegaHAL: WITHIN MY PENGUIN LIES A TORRID STORY OF HATE AND LOVE. • Keyword-based generation helps to make them relevant. User: In 1793 the french king was executed. MegaHAL: HA HA! CORRECT. ALTHOUGH, EXECUTED HAS MULTIPLE MEANINGS. • Users talk to this thing for hours on end, and respond emotionally.
SANDBOX WORLDS • Graphics got fast and detailed, so players wanted more interaction. • Physics improved, and is now practically mandatory. • It's fun to “muck around” within these “sandbox worlds”. • AI required to populate the world with believable characters.
INTERACTIVE DRAMA • All the world's a stage – add a compelling story to the mix. • Façade, by Mateas and Stern, is an example (InteractiveStory.net). • Dialogue is a necessary component. • AI required to present the story, and process the dialogue.
AUDIENCE OR PROTAGONIST? • Cut-scenes are non-interactive and quickly become repetitive. • Sandbox worlds lack dramatic tension. • Rather than “being” the protagonist, the player may “act” in their role. • AI required to interpret player action with respect to its context.
GAME AI • Typically, only 5% of resources spent on AI. • We'll soon have the power of a desktop PC of the early 1990's. • Create a compelling experience on such technology. • We need to look beyond the search-and-optimise of GOFAI.
SUMMARY • AI is required to populate the world with believable characters. • AI is required to present the story. • AI is required to process the dialogue. • AI is required to interpret player action.
PLAYER MODEL • Requirement: Interpret player action. • Goal: Balance player freedom with narrative consistency. • Goal: Enable cinematic presentation of gameplay sequences. • Abstracted commands – context provided by story, world and subject.
DIALOGUE ENGINE • Requirement: Process the dialogue. • Goal: Ubiquitous, believable conversations. • Voice acting, localisation and input devices limit the possibilities. • Move beyond menu-based conversation and “taunts”.
DIALOGUE ENGINE • Adopt Mann's “Dialogue Macrogame Theory”. • A conversation is a sequence of short dialogue games. • Players take turns speaking, and negotiate game entry and exit. • Dialogue Engine moderates the games, and issues potential actions.
DRAMA MANAGER • Requirement: Present the story. • Goal: Select a story thread and direct other components. • Provide potential dialogue games to the Dialogue Engine. • Constrain the behaviour of the Player Model and the Cast. • Inform the Camera, etc.
STORY ENGINE • Requirement: Present the story. • Goal: Provide potential story threads to the Drama Manager. • Story threads specify cast, dialogue, locations, props, etc. • Story Engine selects relevant story threads opportunistically. • Each thread is a network of potential dramatic moments, or “beats”.
CAST MANAGER • Requirement: Populate the world with believable characters. • Goal: A world of 1.5 million inhabitants. • Goal: Embodied, autonomous, reactive and conversational NPCs. • “Extras” provide background, and ad lib when necessary. • “Heroes” participate in the overarching story.
CAST MANAGER • NPCs have personality, emotion and a hierarchy of relationships. • Extras are spawned at “random”, according to demographics. • Extras behave reactively, foraging the environment and exiting ASAP. • Heroes are hand-crafted, and inhabit the world persistently. • Heroes behave deliberatively, as specified by story and routine.
WORLD MODEL • Provide world knowledge to Story Engine and Cast Manager. • Manage non-story events that occur throughout the world. • Provide appropriate dialogue games for talking about them.
WORLD MODEL • Adopt Milgram's “Six Degrees of Separation”. • A “grapevine” extends from the NPC to an item of world knowledge. • Probability of existence may be estimated. • Each NPC appears to have their own knowledge of the world.
CONCLUSION • Suspension of disbelief requires believable worlds. • Technology only worth using if it enhances the player's experience. • We have the resources to build an AI team to achieve them. • And the opportunity to create a groundbreaking, immersive game. • JasonHutchens@gmail.com