A complete 3-D game development suite written in Java
Magic Another Game Engine
3D Procedural Game Engine Using OpenGL
Game engine to build text adventures.
An isometric arcade-style game of skill, puzzles and exploration
A simple math library for games and computer graphics
State Management and Multiplayer Networking for Turn-Based Games
Spring is a free RTS engine developed for Windows, Linux and Mac OS X.
Opensource Game Studio
IGS Labs
Role Playing Game Engine
Gomoku Game: Playing with Computer