iMUSE
iMUSE (which stands for Interactive MUsic Streaming Engine) is a game engine specifically designed to synchronize music with visual action in a video game. The point of iMUSE is to dynamically make the music fit the scenes, characters and moods of the game, much like a movie soundtrack. LucasArts patented it under US Patent No. 5,315,057. It was added to the SCUMM engine in 1991.
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 Star Wars LucasArts titles such as Star Wars: X-Wing, Star Wars: TIE Fighter, Star Wars: Dark Forces and Star Wars: X-Wing Alliance.
Philosophy and technique
A typical example is in the flight engine of X-Wing: While the player is flying, the engine plays the normal soundtrack, loosely based on the Star Wars theme. When a Rebel or Imperial craft enters the area, the music is interrupted by a brief "Rebellion theme" or "The Imperial March" cue.
Other cues play when a mission objective succeeds or fails, when the player hyperspaces back from a mission, etc.
The interruption of music, insertion of short cues and continuing of the music uses a sophisticated algorithm which makes a smooth and almost unnoticeable transition. The result is like a unique, flowing piece, with its own variations that match the story.
