CoffeeMud is a text-based virtual reality gameengine (a MUD). It is a mature, full-featured Java codebase. It includes web (HTTP) and email (SMTP) servers, chat (IMC2 and I3) and web clients, and supports ANSI, MXP, and MSP.
Crimild Engine is an open source scene graph based engine which purpose is to fulfil the high-performance requirements of typical multi-platform two and tridimensional multimedia projects, like games, simulations and virtual reality.
Framework and set of object-oriented and/or generic libraries designed for games and virtual reality simulations. Abstracts interfaces of APIs and provides additional general and high-level functionality for rapidly creating solid applications.
OpenReality will be a 3D Engine Library for development of Games, Virtual Reality and 3D Visualization applications. It will be very intuitive, and strongly object oriented. Of course, performance will have a great weight on the project´s decisions.