Upgrade to the full version and unlock eight new campaign missions, a more difficult AI, a local multiplayer, and perhaps most excitingly, a robust online multiplayer mode. Features Play the AI on 2 different difficulty settings. 8 more fun campaign missions. Battle your friends face to face with Pass and Play. Play against many more opponents online. Challenge a friend to online Player v Player combat

— Activation Details —

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.