What my rapid review of these remarkable articles reveals is that music is crucial for games and not merely a trivial and minor aspect. It is modular, dynamic, interactive, narrative, historic, avant-garde, popular, creative, educational and many more things. If you would like further to explore these multiple directions, I recommend both of these inspiring volumes.
Popular Music
(review of this book and another on a similar subject)

By underlining key issues, grappling with pertinent terms, outlining specific methodological tools, and contemplating core critical issues, this publication represents an admirable attempt to highlight not just the necessity of video game music studies as a field of scholarly enquiry, but so too the surprising level of maturity that it has already achieved in its relatively short lifetime.
IASPM Journal