I'm not new, lol! OpenSim is however, new to me so you're partially correct.
"OpenSimulator is an open source multi-platform, multi-user 3D application server. It can be used to create a virtual environment (or world) which can be accessed through a variety of clients, on multiple protocols, see Connecting. Optional Hypergrid allow users to visit other OpenSimulator installations across the web from their 'home' installation or grid. In this way, it is the basis of a nascent distributed Metaverse."
It might be an OS item only... Be