Complex sentence: The first game to use the iMUSE system is and has been used in all LucasArts adventure games since, it has also been used for some non adventure LucasArts titles such as TIE Fighter or X-Wing Alliance.
Split into simpler sentences: The first game to use the iMUSE system was and it has been used in all LucasArts adventure games since. It has also been used for some non adventure LucasArts titles such as TIE Fighter or X-Wing Alliance.