Toni Westbrook authored a new C64 game called Shredz64, bringing the best game of all time to the best computing platform of all time:
You can use the real Guitar Hero controller using the PSX64 PS2-to-DB9 converter which Toni also created. This takes the game controller input and maps it to the appropriate up, down, left, right and potentiometer lines for the Commodore.
Shredz64 uses the internal SID audio processor to play any of your favorite SID tunes. In addition to the built-in songs, you can import new SID files and even create new levels by editing note tracks (using the game controller, naturally).