Exipnos is an Open Source, network based 3D virtual reality platform. The platform is intended mainly (but not exclusively) for eLearning applications. Role Player or Adventure Games might as well be developed and hosted on Exipnos.
MindGate is a virtual reality multiuser client - server system written in Java. The purpose of the system is to provide communication, persistence, 3d streaming support for users which are imersed into virtual reality worlds - stored anywhere on the Web.