Fruity Bat is a Flappy Bird clone, made in Ruby, that was developed while live-streaming on twitch.tv. It uses the gosu gem.
You can view a recording of the stream here: http://youtu.be/QtIlyU2Br3o
First you need to have bundler installed:
gem install bundler
Next, install all the dependencies using bundler:
bundle install
Finally, you can run the code:
bundle exec ruby game.rb