  Player experience (PX) evaluation has become a field of interest in the game
industry. Several manual PX techniques have been introduced to assist
developers to understand and evaluate the experience of players in computer
games. However, automated testing of player experience still needs to be
addressed. An automated player experience testing framework would allow
designers to evaluate the PX requirements in the early development stages
without the necessity of participating human players. In this paper, we propose
an automated player experience testing approach by suggesting a formal model of
event-based emotions. In particular, we discuss an event-based transition
system to formalize relevant emotions using Ortony, Clore, & Collins (OCC)
theory of emotions. A working prototype of the model is integrated on top of
Aplib, a tactical agent programming library, to create intelligent PX test
agents, capable of appraising emotions in a 3D game case study. The results are
graphically shown e.g. as heat maps. Emotion visualization of the test agent
would ultimately help game designers in creating content that evokes a certain
experience in players.
