Virtual reality (VR) technology generates an interactive virtual environment (VE) creating unique users' experiences. A central part of VR experience is being immersed into a VE. Immersion factors, such astechnological and perceptual features, are described in detail in non-immersive VR settings. However, advancements in VR technology, such as head-mounted displays with high resolution and precise motion tracking systems, that improve interactivity within the VE are not yet adequately considered. We conducted twelve semi-structured interviews immediately after respondents played highly immersive games using state-of-the-art VR equipment to identify novel immersion factors in this setting. The findings yield eleven immersion factors across three categories: (1) physical and physiological aspects, (2) cognitive and affective aspects, (3) social interaction and shared experience. Within these categories factors named "shared experience" and "translating actions from physical to virtual reality" were found as novel immersion factors in the VR context.