A complete 3-D game development suite written in Java
scene-oriented, flexible 3D engine (C++, Python, C#, Java)
Full featured MUD server with all the trimmings.
An online multiplayer turn based strategy game and board game engine.
A multiplatform game engine for interactive fiction experiences
UtiliGame is a light-weight game engine written in Java.
A game engine in java for 2D strategy games
Free MMORPG Engine. Develop and host graphical browser-based games.