By popular demand (well, one request), I’m writing up my notes on Richard Evans’ talk from AIIDE. Richard Evans is currently working at EA/Maxis on the Sims 3. He talked about how the work they’re doing to make each Sim unique and distinct. They’re goal is to make them more individual and more social at the same time.

They have a large pool of discrete traits. Each Sim gets a selection of about five from the pool of traits. Some traits are mutually exclusive, for example, a Sim can be modest or have a big ego. A Sim can hate TV or love TV.

They’re doing their work on the game mechanics in a 2D prototype. It’s a simple sprite world with box graphics, but the simulation it’s running is complete. Richard showed us several demos of the topics he was discussing in action. He had a Sim that hated TV and one that loved TV. It resulted in a funny setup where one Sim would turn on the TV and the other would promptly turn it off.

Besides individual traits, another big addition is that the Sims actually do long term planning. He created a Sim and gave it the workaholic trait. Then he got the Sim a job as a waiter, which is on the restaurant track. The Sim then independently went off to try to level his cooking skill. It bought a cookbook and read it, it bought ingredients and started cooking. It called his boss and invited him over because becoming friends with your boss will get you promoted.

Their second main goal is to make the Sims more socially aware. Richard previously worked at Lionhead Studios on the creature AI for Black & White. A problem in both Black & White and the Sims that Richard found was where the creature/the Sim will interrupt a social situation, for example, attending to a bodily function in the middle of a conversation. This is because they had no awareness that doing so was interrupting something.

The Sims 3 adds social situations. Some examples he gave were visiting (what to do while over at another Sims), mealtime, bedtime and dates. He showed a demo where the Sims recognized the situation and knew what was appropriate or inappropriate. For example, it’s inappropriate for a visiting Sim to watch TV, take food, or sit on the bed of the host. This actually allows for more interesting interactions where you can force you Sims to violate social norms and the other Sims will recognize this and react. It is fun to be naughty but you can only be naught if people know what’s appropriate.

Richard then talked about Garfinkel’s breaching experiments where students were instructed to purposefully break social norms.

He showed how the actions available to the Sim depend on context. At any moment there are many competing contexts scored and sorted by saliency. There is also some amount of memory of past events. If a Sim violates a social norm, they’ll later have the option to apologize for it.

In addition to the larger prototype, they make a lot of smaller standalone prototypes. If they find one of them successful, they’ll roll it into the larger prototype. He showed a couple of these prototypes. One was a diary generator which takes a given set of events and then spits out a journal of it. They had knobs to tune how formal or informal it was, and how truthful as well. It was neat, though not sure how much gameplay there is in something like that.

The talk was about a month ago now, so unfortunately I’ve forgotten some of the details of the talk. It was quite interesting and I love seeing how other companies do things. The prototype was a great tool. While it was in no way something you could give to the public to have fun with it had everything the game designers needed to figure out how to make the mechanics of social interaction work.

I’m looking forward to seeing how they continue to add to the franchise.