Penny Baillie-de Byl summarizes the reasons why we do things as a force of nature. Nature (which almost sounds like “god” in her exposition) wants us to do certain things (namely survive as individuals and survive as species). To make sure that we do these things, nature rewards us when we do them. The rewards come in the release of chemicals in our bodies that make us feel good. A long time ago, and for a very long time, hunting and gathering were necessary for survival. This is why nature rewards us when we hunt or gather.
While hunting and gathering has disappeared as an activity for most people, the natural reward system is still in place. This is why we experience pleasure when we play games.
Anyway, disregarding whether this is a satisficatory explanation of human behaviour, it struck me that it might be a plausible model for the behaviour of autonomous characters.
I’m always interested in finding ways to concentrate on the ear when trying to paint an eye (Kees Vollemans). So rather than starting from the individual’s motivations, drives, preferences and moods to make a character act autonomously, we could play nature and build a reward system for NPCs. Something like a list of actions that we want the NPC to perform. And for each action that it performs, it gets a number of pleasure points. That way, a characters only needs one motivation: to gain pleasure points.
To differentiate personalities, this list of actions, and the points awarded for performing them, could be slightly different for each character. The list should also probably be dynamic. So we can change it from above if we want a certain thing to happen. Or to prevent a character from continuously doing the same thing to increase its pleasure points. Perhaps the number of points that the NPC gets for performing a certain action is relative to the amount of time that has elapsed since it last performed the action. That way each time an action is performed, the number of points decreases. But over time, the award increases.
It’s scary to reduce human behaviour to such mechanistic systems. But that is not the point. We don’t want to create autonomous organisms. We don’t want to recreate human individuals. We want to create characters whose behaviour has a dramatic and emotional effect on the player in the context of a narrative environment.