Any other answers but Shadow of the Colossus, Shatter and AudioSurf are just... wrong.

Music? Gameplay? Seriously, it's ridiculous to suggest anything other than a rhythm game.

I think maybe you actually meant to ask which game wove music most effectively into its narrative, or perhaps experience.

Groov. XBLA. $1.

Every action you take in this dual stick shooter creates the music. It's just so incredible. I died so many times unnecessarily just making music and no even paying attention to the enemies. If you have an Xbox 360, you owe it to yourself to snag this hidden gem. One of my favorite games of this generation, and the best music-based game I've ever played. Very challenging, too.

This. And the music for Ico is very well chosen too. It works so well in Ico since the music keeps it distance most of the time which makes it all the more effective. The problem with most games is that you get tired of the music long before the game is over, not in these 3.

I would add Pixeljunk 4AM too, although it's debatable if that's a game.

The last stage of Pixeljunk sidescroller also stands out for me, perfect marriage between music and on screen action.

Again, I must say

Guitar Hero

Super Metroid. It's music makes you feel so isolated when playing. Sometimes I have to abruptly quit the game because I start getting antsy after a while. (same goes for Metroid Prime)

If there's one thing Nintendo promised with the metroid games is that the music really does make you feel like you're all alone in a deserted planet. The music makes you feel anxious as hell, and for me with anxiety problems, it's not pretty.

In that case -- that we're talking more about the narrative than the gameplay -- I might agree. Ocarina, Majora, or Wind Waker. I'd have to think about it more.

If we're talking about the overall experience, it's much more debatable for me, but the Zelda series as a whole is definitely up for consideration.

Any answer other than the Dreamcast classic Rez is just... wrong.

Ico is better than SHadow of the Colossus. Yeah I said it.

Oh and

Fear is the mind killer...

I was thinking of Eternal Sonata but I couldn't think of the name at first and accidentally stumbled onto The last symphony. A fascinating read.

In a brilliant touch, the team integrated fitting symphonic musical elements; while the player can get information on every object they unearth in the house, they can get further clues about the interrelationships between those things and what story conclusions might be drawn by the musical parts that play when objects are placed side by side in the player's packing truck.

As the player builds a logical grouping of objects, a harmonious symphony swells. The music in the game is absolutely lovely, and perfectly compliments the soft, hand-drawn art.

"I worked with a really cool team of students," says Fernandez Vara, adding that using sound and music as a hint system challenges players -- who don't normally use listening skills when playing -- to look at problem solving in a new and refreshing way.

http://www.gamasutra.com/view/news/178188/Inside_The_Last_Symphonys_harmonious_narrative_experiment.php#.UJidGWfoyK8

I'll try it tomorrow.
http://gambit.mit.edu/loadgame/summer2012/thelastsymphony_play.php