iMUSE (Interactive Music Streaming Engine) is an interactive music system used in a number of LucasArtsvideo games. The idea behind iMUSE is to synchronize music with the visual action in a video game so that the audio continuously matches the on-screen events and transitions from one musical theme to another are done seamlessly. iMUSE was developed in the early 1990s by composers Michael Land and Peter McConnell while working at LucasArts. The iMUSE system is patented by LucasArts, and was added to the fifth version of the SCUMM game engine in 1991.
iMUSE was developed out of Michael Land's frustration for the audio system used by LucasArts while composing The Secret of Monkey Island. His goal was to create a system which would enable the composer to set the mood via music according to the events of the game. The project was much more daring than he had imagined. He then brought in an old friend, Peter McConnell, to collaborate on creating the system which they later patented together. The first game to use the iMUSE system was Monkey Island 2: LeChuck's Revenge, and it has been used in all LucasArts adventure games since. It has also been used for some non-adventure LucasArts titles such as the DOS version of Star Wars: TIE Fighter.
One often cited example of the iMUSE system is at the very beginning of Monkey Island 2 where Guybrush finds himself in Woodtick, the small town on Scabb Island. Whenever Guybrush walks into a building, a variation of the Woodtick theme plays, each with a different instrument. When Guybrush then walks out again the music has a closing flourish that fades out to the basic Woodtick theme.
^US patent 5315057, LAND MICHAEL Z [US]; MCCONNELL PETER N [US], "Method and apparatus for dynamically composing music and sound effects using a computer entertainment system", assigned to LUCASARTS ENTERTAINMENT CO [US]