Frets on Fire just might be the perfect freeware game for you.  Frets on Fire will challenge your musical skill and help you develop some fast fingers as you rock along to some kickin' tunes. Played entirely with a keyboard, you'll be on fire in no time, with the ability to add more songs down the road from the entire Guitar Hero catalog, or from the growing list of songs (hundreds) made especially for Frets on Fire.