Size variation and flow experience of physical game support objects

This paper is about designing and evaluating an innovative type of computer game. Game support objects are used to enrich the gaming experience [7]. The added objects are active but are simpler than real robots. In the study reported here they are four helper ghosts connected to a traditional Pacman game. In earlier projects we already found that children consider such type of additions attractive. We also found that the computer screen tends to draw the users attention away from the support objects; therefore, the new set-up described here was designed to facilitate simultaneous screen and object-based interactions. The object interaction is essential for playing the game and not just an add-on. In order to develop a better understanding of this type of interaction and thus create future games more systematically, we did a formal user test in which we systematically varied one parameter. Three different versions of the system have been built and tested; they differ in the size of the ghosts (42cm, 15cm, 6cm high). We report on the playability of the new game, the embodiment of the interaction, the degree of flow that could be achieved and the effect of the size of the game support objects on both flow and scores. The lessons learned include a number of insights regarding the design of physical game extensions. The most important finding is that the size of the objects is relevant with respect to fun. No significant effects of size on flow were found. Visibility and distances are critical, however. Observations and interviews indicate that certain ergonomic aspects of the interaction, which are a consequence of the size parameter variation, are really decisive, not the perception of size as such.