Seaweed is software to design and play economic-game experiments.
Seaweed can create simple two-player economic games with symmetric actions and one decision per screen. And your game is ready to be played by randomly paired people on the Internet.
Chess++ is a modern multi platform 3d chess game implementation for (at least) GNU/Linux and Windows with user programmable chess rule sets, a client software application (chesspp), and a server application (cheppd) by which all the games are managed.