Without a doubt, the Tracker 4C is currently a niche product, because while it can add a lot, eye tracking in games is still a new concept, but it is gaining momentum. Currently there are over 40 games that support Tobii eye trackers, but the company expects there to be over 100 by the end of 2017. My personal suspicion is that this number will continue to grow, especially as VR matures and grows in popularity. There is definitely overlap between the capabilities of the Tracker 4C specifically and the head tracking VR systems currently enable, and while the head mounted displays will have technical advantages over the Tracker 4C, they cost more than $149 and require more than a USB 2.0 port to work. (By the way, I seem to recall reading at some point that VR headsets will likely come to incorporate eye tracking systems for that extra layer of interactivity but also to intelligently reduce the detail in the periphery of a frame.)