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GDC 2012: Sims team's Graham says ambient AI tells better stories

NPCs are stupid, says Sims lead AI programmer David Graham. He says ambient AI for NPCs is the next frontier for realistic game characters and stories on the whole.

Brandon Sheffield

March 5, 2012

2 Min Read

During his AI rant, Sims lead AI programmer David Graham spoke to the importance of ambient AI. "We're getting better at enemy AI," he says. "We're also getting better at companion AI as well ... A lot of those 90s era escort missions from hell are coming to an end." Games like Dragon Age even let you build your own basic AI for your characters. But why did we stop there? What about the rest of the world? Also in Dragon Age there are boring cycles for background characters, like a guy fixing a wagon for ever. Background characters are important, Graham says. In Deep Space Nine for instance, all the background characters are actually doing things. They have specific actions. "If these were just looping animations, it'd be like 'wow, this isn't a very fun station to be on,'" he says. "The design manual for AI is life," Graham reminds us, quoting AI Summit coordinator Dave Mark. Thus, people watching is very important. "I really strongly think that AI programmers need to do this all the time." Ultima 7 had NPCs that had schedules, way back in 1992. Why don't we have these in more games, he asks? Graham worked on an adventure game called Rat Race, which takes place in an office. "There are people who wander around our office autonomously," he notes, each with their own agendas and without constnat loops. "It was a very simple utility-based design that made this stuff happen," he says, which makes the place a vibrant living world. Graham then showed a slide with some of the AI code, written in XML. The comments in the code told an actual story, outlining the things these NPCs like and don't like to do, and adjusting their affinities. If you have intelligent NPCs, you can tell a better story. "Ambient AI adds to the immersion of your game, and it can be done simply and cheaply."

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