The Sims was largely made possible by a bunch of simulated ants. During an interview with Doom creator John Romero at the IGDA Leadership Forum dinner last Friday, Wright revealed that his previous title, Sim Ant, was a key inspiration for -- and the basis for the core emergent gameplay in -- The Sims.
"We decided to program Sim Ant as close to how real ants work as we could, which means that they're actually responding to pheromone trails, and the intelligence is distributed environmentally," Wright recalled when asked how The Sims came about. "We were able to get very complex behavior out of the ants just using these pheromone distributions. So I started to wonder how much of human behavior I could simulate the same way." As it turns out, a lot.
"The basic engine for The Sims really ends up being one of any pheromones. Every object in the environment is sending out an 'advertisement' of pheromones in a particular flavor. The flavors are the eight basic needs of the Sims. So they can advertise 'food,' 'energy,' 'fun,' 'social,' 'hygiene.' Every object is described in those terms, being the collection of pheromones that it broadcasts," Wright explained. "A Sim is always sitting there, smelling all of the pheromones around it saying, 'oh I need to be clean, or I need to be fed' -- whatever -- so they follow that pheromone trail to the closest object that's producing it. The advantage of that -- the whole point of that -- was that we could add new objects into the game later without the Sims having any foreknowledge of what the objects were, as long as they had these pheromones."
Romero began to ask Wright if he thought actual humans might somehow work this way, but stopped himself. He was probably picturing the audience as a group of hideous ant people, or imagining he could see clouds of pheromones wafting about. Even the guy who thought up the Doom demon would be grossed out by that.