Portal 2 has a great soundtrack, but just as important as its quality is how it's used in-game. The way Portal 2 uses music in-game is something I haven't quite seen anywhere else, even after 10 years.

Sources used: Plogue interview with Mike Morasky: https://www.plogue.com/mike-morasky.html Techniche Interview: https://www.youtube.com/watch?v=z37kBD0DYqg GamesRadar interview: https://www.gamesradar.com/portal-2s-dynamic-music-an-interview-with-composer-mike-morasky-and-five-tracks-to-listen-to-now/

0:00 Intro 0:25 Dynamic music 3:09 Diegetic music intro 3:48 Portal 2's use of diegetic music 5:22 Other examples 6:44 Conclusion