Frets on Fire a.k.a. FoF is a free and open-source music video game that is very similar to the commercial Guitar Hero series. Players can use a keyboard, control pad or other guitar type controller. The objective is to play to the markers on the screen that sync to the songs rhythm, with the aim of completing the song and scoring points.
Intel powered Mac
Mac OS X 10.5 or newer
OpenGL compliant graphics card
Free download at fretsonfire.sourceforge.net