Context. Gaze based interaction in video games is still a developing field, and is mostly used as an off-line evaluation tool or a replacement for traditional input methods. This thesis will look closer at the prospect of using eye tracking as an additional input to be used alongside the traditional methods of input to improve the immersion and performance of the player.

Objectives. To implement a gaze based interaction method into arst person adventure in a way to improve player performance and immersion.

Method. Using the Tobii REX eye tracker, 18 volunteers participated in an experiment. They played two versions of a game in an controlled environment. The versions had the same mechanics and game elements but only one of them had eye tracking implemented. After the experiment the participants answered nine questions about which prototype they preferred.

Results. All participants' scores were in all cases but one, lower when using the eye tracking input method, compared to the traditional one.The time it took for the participants to complete the game was longer for everybody. 16 out of 18 players also felt more immersed in the game while using eye tracking compared to playing with the traditional input method.

Conclusions. The results from the experiments provided evidence that the interaction method designed for this thesis did not improve player performance. The results also showed that the interaction method did improve immersion for most players.