I think what Bloth means is not just having music accompany the action, but determine or set the game's context and mood, and even suggest underlying themes. For instance, an overused trope in horror movies and games is having tense music (usually strings) with unresolved harmonies or a certain level of dissonance to reflect stress or anticipate scary situations.
Maybe what games could incorporate, now that high quality soundtracks are an option, is the leitmotif concept largely used by composers like Richard Wagner. Some games that do use it are the original Prince of Persia (1989) and Loom, both games from the old MIDI era. Essentially this entails composing short themes for different elements and concepts (sword theme, falling theme, love theme, enemy theme) as mundane or abstract as you wish, and then using them to enhance or highlight situations, objects or characters, suggest their motivations and even create entire musical pieces by mixing and arranging these conceptual pieces. For instance, mixing the spear theme with the fate theme with the sorrow theme to illustrate Odin smiting Sigmund, followed by a mix of the sadness theme and the valkyrie theme (disclaimer: doesn't represent the actual composition, just an example). Or using the mystery or psychotrip theme structure around a character to suggest he might not even exist.
Anyway, so many possibilities. Music is powerful and can participate in-game, not just accompany it.