A method for playing a song of a particular musical style is disclosed. Program instructions are executed, and one or more music composition algorithms are applied to song data in accordance with a song data structure to generate music output for the song. A plurality of levels of predetermined musical styles are determined, and values of one or more parameters in accordance with the song data structure are limited to predetermined ranges corresponding to the particular musical style. A first user input is received for selecting a particular musical style. A second user input is received for one or more musical components, and music characteristics in accordance with the song data structure corresponding to the musical components are modified in accordance with the user input, and the user input modifies the values of one or more parameters within the predetermined ranges. In response to the user input a modified song may be created based on user modifications to the music characteristics. The user input for selecting a particular style may select a level of a particular musical style, and the predetermined ranges for a particular musical style at a first level of musical style may provide a greater range for modifying the musical characteristics as compared to the particular musical style at a second level of musical style. The user input also may modify music output corresponding to one or a plurality of instruments, audio samples or microphone input. The modified song may be stored for subsequent playback and/or played in real time as a live performance.