Serious Sam HD: The First Encounter Steam CD Key
Serious Sam HD: The First Encounter is a visually upgraded and fully Steam supported remake version of the original high-adrenaline single-play and 16-player co-operative arcade-action FPS.
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.