Frets on Fire turns your keyboard into a makeshift guitar. Rock out to your favorite jams with this absolutely free contribution to music-making from Finland. The aim of the game is to play guitar with the keyboard as accurately as possible. Frets on Fire is open-source and includes a unique inverted keyboard gameplay style; support for guitar controllers and generic joysticks; a song editor for making your own tunes; the ability to compete with others on the World Charts; hundreds of songs composed by the community; and support for importing Guitar Hero and Guitar Hero II songs. It's Christmas come early!
Homepage - http://www.unrealvoodoo.org/projects/fretsonfire/
Download page - http://fretsonfire.sourceforge.net