The VR community had heavily invested in the STEM kickstarter a month or so before PrioVR's kickstarter was up. I think this was a big reason that the first one failed. The marketing of the technology also failed because they didn't show any integration into any existing games like the STEM system was doing at the time. The fact that the Razer Hydra was already in the hands of folks meant they could see other people using what is in sense a prototype for the STEM system. Also PrioVR is only relational to your own body and doesn't track where you physically are in a room which was one of the major concerns people wanted addressed.