Audiosurf is a puzzle/rhythm hybrid game created by Invisible Handlebar, a personal company created by Dylan Fitterer. It's track-like stages visually mimic the music the player chooses, while the player races across several lanes collecting colored blocks that appear in sync with the music. The music used in the game is chosen from the user's own library, from almost any DRM-free format, as well as standard redbook CDs; in addition, Audiosurf includes the entire soundtrack to The Orange Box as part of the download.Go to: http://store.steampowered.com/ and download STEAM client
Click “Install Steam” (from the upper right corner)
Install and start application, login with your Account name and Password (create one if you don’t have).
Please follow these instructions to activate a new retail purchase on Steam:
Launch Steam and log into your Steam account.
Click the Games Menu.
Choose Activate a Product on Steam…
Follow the onscreen instructions to complete the process.
After successful code verification go to the “MY GAMES” tab and start downloading.