T3bftw is a project mainly written in ..., it's free.
threedeeblocksforthewin
Simple game to demonstrate use of Websockets, Ruby Event Machine and Coffeescript
Install all gems:
cd server
bundle install
Start the server:
ruby server.rb
Start a client? Just open client/index.html and you're good to go!
Install guard:
cd client
bundle install
Run guard while developing in Coffeescript:
guard
Done!