1. A method of scoring a performance of a guitar part in a rhythm-action game, executed on a game platform in communication with a display and a controller, comprising: (a) receiving an input performance from the controller comprising at least one input chord note, each input chord note comprising an input string value corresponding to a struck string and an input fret value associated with the input string value; (b) providing a reference performance comprising at least two reference chord notes to be input at a target time, each reference chord note comprising a reference string value and a reference fret value associated with the reference string value; (c) determining a degree of matching between the input performance and the reference performance; and (d) assigning a score to the input performance based on the degree of matching.