jDip is a tool for mapping, managing, and adjudicating Diplomacy games. It has a simple but powerful graphical interface, with a richly customizable map display. Windows, Linux, Mac OS X, and Solaris are supported. Over 25 variants are supported.
The Java AI Gaming Engine is a collection of games that allow easy integration, testing, and competition of AIs. The games that are supported: Hex and Ataxx, and in the future: TicTacToe, Chess, Checkers, Rock-Paper-Scissors, and more.