CoffeeMud is a text-based virtual reality game engine (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.
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.