Virtual Reality (VR) has the capability of fully immersing users into a wide variety of gaming experiences where the sole focus of the user is on that experience itself. One problem that often occurs when it comes to VR experiences is that of simulation sickness (SS), which is particularly prevalent when the user is forced to play at an abnormal posture due to physical limitations or specific treatment procedures. In this paper we report on a between group study comparing the effect of SS mitigating factors for two postures: seated and lying-down on one's back (known as the supine pose). A 3D recreation of the popular game Pacman (Namco, 1980) was developed specifically for VR. Each subject participated a total of six sessions of six minutes each taking place over the course of two to three weeks with a two to five day minimum and maximum between each session, respectively. At the start and end of each session participants were asked to fill-in the Simulator Sickness Questionnaire (SSQ), allowing to effectively rate the intensity of SS per session. Results show a lack of significant differences when examining participants as a whole regarding the SS decrease in relation with the field of view (FOV) and the rest frame factors. However, when considering the participant experience in VR, it appears that the lying-down pose does trigger simulation sickness symptoms for more proficient participants whereas they do not report such symptoms for the seated posture.