 Much of Mizuguchi's time during development was listening to music to inspire his designs.A key element for Mizuguchi was allowing for mistakes and fluffs from the player—penalised in other titles within the genre—to be incorporated into the score of "Rez".The musical gameplay was developed following a call and response approach (the audience responds to something from a singer or performer), similar to that of what a disc jockey would do to get reaction from the crowd.