One of the great things about video game music is that, like film orchestration, it underscores the actions that are taking place and sets the mood for the situation you're in. If you're fighting an enemy, the music often changes to something more upbeat with perhaps a darker timbre. If you're in a small town and surrounded by friendly villagers, the music is most likely calm and melodious. In addition, music cues are often triggered by one's effectiveness within the environment. For example, if you win a battle or complete a stage, a victory fanfare often plays to indicate that you've done a swell job. Conversely, if you (or a supporting character) die(s), then a lachrymose dirge may accompany you (or, you may get a "whoopsy-daisy" ditty).
As the music in video games (and the technology to support it) evolved, these soundtracks gained the ability to travel right along with the player and his or her performance. It's an experience that is unique to video games, and the assault on your ears may be what spurs you into victory.