Audiosurf is the kind of bizarre genre-defying game you could only expect from an independent developer. And, thanks to the establishment of online game distribution services such as Valve's Steam platform, accessing indie titles like Audiosurf is easier than ever before—provided that you don't mind whipping out your credit card a little more often. In Audiosurf's case, it might be a worthwhile thing to do. Gameplay

Audiosurf is a hybrid music/puzzle/driving game. The player's job is to steer a high speed ship from a third person perspective down a winding multi-lane roadway. It isn't just any road though—it's a highway that responds to music. When the music is calm and slow, the road ascends, and the player's ship climbs the hill at a relaxed pace. When the music is loud and frantic, the highway turns downhill and the ship accelerates to breakneck speeds. The road also reacts to music in some other ways, like bouncing to a strong beat and providing tunnels at particularly intense points in the song.

While all of this is happening, the player needs to score points by creating clusters of colored cars. The cars are rectangular blocks that come down the road toward the player to the rhythm of the music, like the notes in Guitar Hero. When the player's ship touches a car, it is locked down onto a grid underneath the ship. To score points, the player needs to make clusters of three or more cars of the same color on the grid. There are powerups that help create larger clusters and end-of-level point bonuses for satisfying special requirements, like making a cluster of a certain size or collecting 95% of the cars of a specific color.

There are a number of different gameplay modes across three difficulty levels, but they are variants of the same core gameplay, providing different balances of twitchy action and puzzle-style block organization. The multiplayer mode lets two players playing on the same system each have a ship and two lanes of the road to manage, tracking both their individual and combined scores.

What sets Audiosurf apart from other music games is its ability to generate levels from almost any music file that you can provide. While the game comes with some of its own music (the current release of the game on Steam comes with the Orange Box soundtrack and four other songs), Audiosurf really shines when it transforms your favorite album into a glowing, pulsing game world. Audiosurf also tracks scores online for each song that you play, so that you can see who's playing to the same tunes as you are and how your scores compare.

Graphics Audiosurf's visuals are abstract and colorful, with a lot of shimmering and glowing effects, adding up to a large amount of pleasant visual noise. The game needs pixel shader 3.0 in order to display the effects at the highest settings, but it looks fine (and is much less demanding in the hardware department) on lower graphical levels. One downside in the graphical department is the lack of variety. There are only three different visual themes in the game, and some themes seem to be associated with certain modes, so if you only like to play one mode, you'll only see one theme.

Sound Audiosurf's best feature by far is its customizable soundtrack. Unlike music games that force players to listen to the same tunes a nauseating number of times for lack of a longer song list, Audiosurf adopts any music the player provides in wma, mp3, m4a, m3u, ogg, flac, wav, or CD audio formats, and generates new levels in seconds. Some of the more ambient tracks provided with the game as part of the Orange Box soundtrack aren't really suited to the gameplay, which benefits from music with a strong beat. Because it's so easy to add songs that are enjoyable to play and listen to, however, the less than ideal tracks that are included are a non-issue. The game also uses sound effects to signal when your ship absorbs a car and when you make a cluster. The sound effects are sometimes obtrusive and conflict with the music, but they can fortunately be turned down or off in the options menu if the player finds them irritating. Stability

The game has a few technical issues and limitations. Currently (two days after release) the game sometimes seems to have problems connecting to the online scoreboards. One other minor annoyance is that sometimes songs that are the same are labeled differently on the online scoreboards, making multiple scoreboards for the same song. There are also some graphical glitches that occasionally occur when the road happens to pass through one of the scenery models. The game uses Steam's auto-updater to patch the program, and it has already received its first update on the day of its release. Hopefully the game continues to receive support and improve.

The most disappointing part of the game, technically, is the limit it places on the length of the songs you can use. While this is understandable, considering that the length of the road that the game creates is a direct result of the length of the song and that a computer has only so much memory, the length limitation renders some especially long tracks unplayable. The game doesn't tell the player exactly what the limit is either, meaning that the only way to find out whether the game will accept a large file is to try it and wait until the end of the loading process to either play it or receive an error message. It's possible that the limit depends on the system the game is running on, but to give an idea of the size of the limit, a laptop with 2 GB of RAM and 128 MB of video memory will accept a twenty minute long song but reject a thirty minute track. Obviously, considering the size of the length limit, almost all standard pop and rock songs will be short enough to work with Audiosurf, but users intending to play hour-long continuous mixsets will run into problems. Controls/Interface

The player can either steer the ship directly using the mouse, arrow keys or an Xbox 360 controller, or use the number keys to cause the ship to jump instantly from one lane to any other. The two player mode lets one player use the mouse and the other use the WASD or arrow keys. Some of the modes have special functions, mapped to the mouse buttons or other keys, which are explained on the loading screens. The controls aren't customizable, but unlikely any player will have issues with the default schemes.

Navigating the menus is simple and straightforward, with tooltip popups explaining all of the modes and options. After each level, the final score screen also lets you choose to play the next song or another song from the same album instantly, but if you want to change albums or modes, you'll be sent back to the main menu. Appropriateness Audiosurf's appropriateness is essentially in the hands of the player. It is, in itself, not at all violent or otherwise objectionable, but, because the game's musical content is provided by the player, the player can easily make the game totally clean or completely inappropriate. One concern is that a couple of the songs that come with the game have questionable (though not explicit) lyrics. Because the game lets you play any of your own music, though, any player that wants to ignore the songs that come with the game will have no problem doing so. Conclusion Audiosurf is a slick, original, and fun title that lets you experience your music collection in a new way. Aside from a few technical issues, the only problem that some might have with it is the price—ten dollars for an arcade puzzle game isn't exactly a steal of a deal, but considering Audiosurf's essentially unlimited content, it isn't a ripoff either. Players who don't mind the cost and want to experience something new and different should give Audiosurf a try.