Stick on 13 Steps from Radiohead's In Rainbows, for example, and the jarring beats, Thom nervy vocals and sparse guitar figures at the beginning give you a stretch of track with sudden bumps and clusters of blocks. Once the bass kicks in and the song builds into the chorus, you're rewarded with faster downhill stretches, lots of blocks and a whole lot of activity on the screen. All I Need from the same album is even better, the game gaining pace and getting ever more hypnotic as the song builds momentum. Air Traffic's anthemic Shooting Star is another winner, the game holding back during the restrained verses then going hell for leather during the big chorus. Put Audiosurf together with the right song, and you get these magic moments where the music and the visuals and the simple but engaging gameplay all come together and you suddenly find yourself taken somewhere new. It can be overwhelming, and you might not want to come back.
To mix things up a little more, the game offers several different modes for each difficulty level. In some, you only get blocks of a single colour and nasty grey blocks that just jam your grid up, making the challenge hitting the coloured blocks and avoiding the greys. In others, you get added abilities, like the power to jump over unwanted blocks or pick up blocks and use them later, or just the wherewithal to shunt blocks left and right with clicks of the mouse button.
Now, all of this would be very interesting for a while just on its own. The more tracks you try on Audiosurf and the more interesting the results you get, the more tempted you are to try out other tracks. You wonder what it's like on heavy rock, on low-key classical works, on Pink Floyd's Dark Side of the Moon (predictably ace, in case you're wondering) and on a little of Miles Davis's cool early sixties Jazz. You may even want to take it to play Daft Punk - (Harder, Better, Faster, Stronger is an obvious winner) - or Glen Campbell's "Wichita Lineman" (I'm not sure how this ended up on my PC, but it works!). The more you like music and the bigger your collection, the worse your Audiosurf addiction is likely to be.
However, there have been games before that use your music collection in a similar sort of way, but what turns what might be just a novelty game into a keeper is the fact that your efforts are tied into online leaderboards for each and every song. Somewhere out there, other people are playing Audiosurf with the same song as you, and as the program's analysis should produce the same results in every case, their score is directly comparable to yours. Can you stand the fact that there are 290 other people out there with a higher score in Mono mode, on Difficulty medium level, on Great Gig in the Sky? Well, you'd better go back in and do something about it, then. Cleverly, you can switch between global and local leaderboards, and even compare scores against any friends you have added to your Audiosurf account. What's more, the game also works with Steam's achievement system, adding awards and points to your profile just like those in The Orange Box.