Utility system

In game artificial intelligence, a utility system is a simple but effective way to model behaviors for non-player characters, by assigning utilities to each action based on some heuristics, and by choosing to perform an action with a high utility. Either the action with the highest utility is chosen, or an action is randomly chosen based on some given probability distribution. In The Sims 3, a modified version of the Boltzmann distribution is used to choose an action for a Sim, using a temperature that is low when the Sim is happy, and high when the Sim is doing badly to make it more likely that an action with a low utility is chosen.