You play the role of a military commander hidden deep within an underground bunker. Your mission – to successfully exterminate your enemy's civilian population whilst disabling their ability to attack your own. Start by launching your battleships, submarines, and bombers in order to decimate your opponent's defences. Scramble together your alliances, but remember only one can stand victorious. Prepare your pre-emptive strike before one of your supposed allies get the same idea. Choose the perfect moment for betrayal, obliterating your opponents with an apocalyptic thermonuclear barrage, but get it wrong and their devastating counter attack will bring you to your knees!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.