EEP — A lightweight emotional model: Application to RPG video game characters

A key factor for the playing experience in modern video games is the behavior of the agents in the game. Recently, several mechanisms have been put forward, with the objective to define synthetic emotional models, so as to make the player believe that the responses of the software agents are motivated, in some way, by emotions. However, there is currently no virtual agent model that satisfies the restrictions imposed by the software development of a commercial video game, namely limited design time and computational complexity but offering flexible mechanisms to define emotional reactions. In this paper, we present the Emotional Elicitation Process (EEP), a lightweight emotional model suitable for use in real-time video game environments. EEP includes: (1) a parametric definition for the character emotional profile, (2) a mechanism to translate events into emotions, (3) a method to update mood state by these emotions, and (4) a mechanism to map mood state into different behavior controllers. We illustrate this model by an example from a commercial role-playing game (RPG) scenario, in which a relatively simple set-up of EEP can produce realistic emotional behaviors consuming few computational resources.