Take the chess graphism, and use it with a chess engine.
Classic backgammon in fantasy setting with a lot of missions.
Cross platform administration tool for Source Engine dedicated servers
A multiplatform game engine for interactive fiction experiences
A 3D, fully concurrent game engine
Role Playing Game Engine
A fun-filled new take on the casual first person arena shooter.
Cross-platform port of Arx Fatalis, a first-person role-playing game
A chess application : game with human and/or computer
A truly extensible cross-platform game engine
A Wargame
C-Lesh is a game programming language for 2D games.
UtiliGame is a light-weight game engine written in Java.
An open source skateboard games engine written in C# and .NET.