The effort that is put into the integration of video game music with the rest of the game is severely underappreciated for a lot of titles. I could list a lot of games from the top of my head that do that well in one form or another. But I'd like to point to two games that stick out of the pack in my opinion.<p>1. Portal 2: There are tons of subtle details to the background music in the game. Thermal Discouragement Beam targets will emit a melodic hum that integrates with the background music when they're activated. In rooms with multiple of them, each one becomes a distinct, randomized voice in the song. While catapulted through the air with an Aerial Faith Plates, the normal background music briefly fades to wind noise - with a procedurally generated retro synth melody on top. Normally, this fits in with the electronic/ambient background music, except in the one segment where there's a Bach piece playing. Then these short interstitials match Bach.<p>2. Control: This game has a segment called "Ashtray Maze". At the start of that segment, the player character puts on the headphones of a Walkman and a song by the Old Gods of Asgard (actually Poets of the Fall) starts playing while the player walks down what seems to be a run down motel hallway from a bygone era. The following section pulls the player through a quick succession of set pieces with big, fast fights and platforming elements, while the song seems to follow its own structure naturally. The pace is determined by the player. Yet, singing passages alternate with purely instrumental ones in a way that doesn't diminish or break the dramatic arc of the song while the tense section of the song invariably coincide with intense player action. It all culminates with the end of the song synchronizing very well with the defeat of the final enemy and exit from the section. The sound track version of the song is almost 8 minutes and the game version is probably split into countless sections (I estimate more than 100).<p>Honorable mention: Journey and ABZU. Both games turn a score recorded by a big orchestra and choir into an adaptive layered soundtrack that is just seamless.