Those of us who worked and actually innovated in VR in the late 80s and early 90s have always been a little worried about Worlds, as they liked to run off to the patent office with all the ideas the collected from the rest of us. All of their patent claims existed in other products - even their first patents were an attempt to claim basic VR tech shown several years before by several groups, including the one I worked with (OnLive Traveler). There is plenty of prior art to invalidate these patents, but in our glorious patent system it will cost millions to do so. And like SCO, their legal zombie remains keep trying to extend old claims and collect something for the little invalid patent portfolio that was passed on when they shut down. The software patent apocalypse continues....