Serious Sam: The Second Encounter, the highly anticipated arcade action FPS sequel to the Serious Sam: The First Encounter, is a high-adrenaline arcade-action shooter heavily focused on frantic arcade-style single player action. In a world where cyberpunk meets fantasy-fiction and advanced technology is mixed with black magic and psycho-powers, Sam travels through the three beautiful worlds, confronting countless Mental's minions on his way to the Mental's base.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.