Dark Chess 960
Dark Chess 960 is a chess variant which has a randomized starting position and "fog of war". That is, you can only see parts of the board that your pieces have access to. The game includes an AI that can play Dark Chess 960 without cheating.
KPanta is an AntiChess program. AntiChess is a game where the objective is to lose the pieces.
MRSD (formerly Ki11egg) is a chinese chess AI engine.
NuclearChess is a chess variant. Whenever a piece is captured, both pieces and all pieces on neighbour fields die. Games are short and fun even for people who usually don't play chess.
Phaserchess is a version of Laserchess that is part of the GNOME project.
VDB Chinese Chess
VDB Chinese Chess is a popular Chinese game that has rules similar to ordinary chess.
VDB Janus Chess
VDB Janus Chess is a game very similar to chess, there is one aditional piece called janus that can move like a bishop and a knight.
A triad of engine, GUI, and communication protocol for Chinese Chess (XiangQi). The two elements, engine and GUI, are interchangeable with any third-party application that follows the communication protocol.