Most music games come with their own soundtrack—which is a problem if you don't like the tunes. (See: Synaesthete.) Audiosurf takes the other approach: It breaks down your mp3s and lets you play a game on top of them, in the form of a spaceship that has to race on a winding track while stars explode at the sound of a hi-hat. Half the fun comes from feeding the game new songs to see how it'll react: Big beats make the track lope and bump beneath you, while sudden crescendos and fast, lurching stops drive it wild. And browsing your collections for the next song that'll make it completely freak out is as entertaining as trying to win.
The actual gameplay mixes racing with pattern-matching. You steer your spaceship back and forth to pick up colored blocks; the more same-colored blocks you combine, the more points you score. Without the audio, it would be a cute casual game, and not necessarily an easy one. You have to watch what's flying at you while managing the blocks you've picked up, which is a little like playing Tetris on your cell phone while you're soaring down the freeway—but not as addictive. Yet high scores are only half the point. Audiosurf will enthrall a wide range of players, from the strategists who master all the tricks to the casual players who just want a great ride.
Beyond the game: Audiosurf has turned a few heads in the music business; Asthmatic Kitty spearheaded a multi-label mix specifically for the game, and the game already pushes indie mp3 downloads.
Worth playing for: Every single song you play—no matter how obscure—gets its own online leaderboard. This gives you the chance to battle for the top slot on a Radiohead song while holding court over all the forgotten mp3s at the back of your hard drive.
Frustration sets in when: Even by indie game standards, the admin interface and manuals are raw. And the lack of support for DRM-burdened iTunes tracks will annoy people who built their digital-music libraries the legal way.
Final judgment: Ranks somewhere between the portable light show and the lava lamp as a non-pharmaceutical music enhancer.