Gameplay is a little different from what gamers might be used to. The premise is that you are marooned in Rapture, an underwater habitat rent by civil war. Your character is caught between deadly forces and hunted by genetically modified "splicers" as well as sophisticated security systems. Supposedly the game never plays the same way twice. But let's talk music.

The first cue, "Bioshock Main Theme (The Ocean on His Shoulder)," opens with an ominous swirl of strings and brass that melts into a melancholy melody that isn't at all what you'd expect from a video game. This is plaintive and haunting, with a few strange little dissonant touches. It's a good taste of what is to come. And it ends with a nice recapitulation of the opening, with additional musical effects that conjure up a door slamming, as if the listener is now trapped in the game's world.

This is followed by "Welcome to Rapture." This is an entirely different piece of music that sounds as if it's been flown in from MirrorMask or some other fantasy world. There's a bit of tympani here but nothing as bombastic and thundering as music in other shoot-'em-ups. Really, Schyman has done something remarkable here.

No two cues are quite the same

"Dr. Steinman," the next cue, is a high-pitched squeal of strings and some muscular ostinatos that quickly become a frantic mélange of fractured time signatures before flying away.

"The Docks" evokes a world of pilings and wharves, complete with hornpipe, creaking spars and ship's bell. It's an ambiance in sound presented in less than a minute. Take a moment to listen to the production here. There are no sound effects per se—it's all done with musical instruments. "The Dash," Cue 5, sounds like every rat on the planet set loose to scamper across the floor. It's 35 seconds of musical skeev.

Other high points are the Moonlight Sonata-like "Dancers on a String," with its touches of Twin Peaks; "The Engine," which sounds like one (listen for the brass syncopating against the pulsating strings); "Empty Houses," sad as a widow's first dawn; and the incredible 32-second crescendo at the heart of "This Is Where They Sleep."

"BioShock is a composer's dream project; I have never been offered such a unique palette to write for," says Garry Schyman. "I even had the opportunity to write a solo piano work in the style of late Rachmaninoff!" That would be Cue 8, "Cohen's Masterpiece," which is a surprise even in this surprising score. I can't imagine this fitting into a video game, but here it is ... and it is lovely. In fact, all the music here is pretty damn good.