Classic (80s) outfits and Zombie outfits can be unlocked by winning stars for specific instruments.

Unlockable	How to unlock
Classic James	150 Stars Vocals
Classic Lars	150 Stars Drums
Classic Kirk	150 Stars Guitar
Classic Robert	150 Stars Bass
Zombie James	200 Stars Vocals
Zombie Lars	200 Stars Drums
Zombie Kirk	200 Stars Guitar
Zombie Robert	200 Stars Bass