Fightly-the-game is a project mainly written in JAVASCRIPT and PERL, it's free.
Fightly, The Game
A game engine for strategic, turn-based, web games.
To test it, install node.js, npm and module socket.io. See https://gist.github.com/579814 and http://npmjs.org/
Launch your web server, and create a link to /dev/client/ in your www folder.
Go to /dev/server/ and start the game : node server.js
Go to your localhost and open three windows with the game: enjoy!