In Super Mario Galaxy, when you first start the game the music is understated then as you progress through the game collecting more power the music crescendos into a full orchestra.
The live instruments are powerful and add a new found depth and expression to the game.
In each location there is a different atmosphere which is created by the music.
Game soundtracks are not something I listen to like a CD, however I do have some of the tracks off Burnout 3 Takedown... although that actually is 'real' music I guess. I think it matches the game well as it is music that you can enjoy listening to in the background but not so overpowering that it distracts from the gameplay.
It is important that the pace of the music is consistent with the gameplay as it would seem out of place if your character was for example fighting a boss to calm, relaxing music o_O
Especially in action games, the music has to sync with game control.
Music is integral to all games, although some rely on it more than others...
In Electroplankton, experimenting with the visual 'characters' conjures an aural simplicity that is actually extremely effective. In Zelda Ocarina of Time, the ocarina plays tunes which enrich the gameplay by offering keys and events, and is very inventive in how you make so many different tunes with just 5 tones.
Somehow got onto listening to the soundtrack of Slumdog Millionaire... It seems to produce an energy which is motivational and exotic sounding and captures the upbeat 'feel good' aspect of the film. I haven't even seen the film yet, but just listening to the music alone really makes me want to watch it!
Don't remember where I found this but they did a good job! Especially love the guy jumping around as Mario haha just shows how much of an influence even the music has an effect on gaming culture, and from the audience's reaction you could so tell they recognised the tunes:
See ya ~Emi ^o^