Portal is a new single player game from Valve. Set in the mysterious Aperture Science Laboratories, Portal has been called one of the most innovative new games on the horizon and will offer gamers hours of unique gameplay. The game is designed to change the way players approach, manipulate, and surmise the possibilities in a given environment; similar to how Half-Life 2's Gravity Gun innovated new ways to leverage an object in any given situation. Players must solve physical puzzles and challenges by opening portals to maneuvering objects, and themselves, through space.

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.