How to get a CD Key for free
1 - First step is to register as the member
2 - Go to the "Earn Coins" page
3 - Choose an offer and complete it with valid information
4 - After completion your coins will be automatically awarded to your account and you can get the Half-Life: Opposing Force CD Key
About This Game
Return to the Black Mesa Research Facility as one of the military specialists assigned to eliminate Gordon Freeman. Experience an entirely new episode of single player action. Meet fierce alien opponents, and experiment with new weaponry. Named Game of the Year by the Academy of Interactive Arts and Sciences.
Instructions to activate steam keys
1 - Download and install the Steam client on your PC.
2 - Open the Steam client, login and locate the Games tab on the top menu. Click this and then select “Activate a Product on Steam…”
3 - Enter your activation key that appears on the email and follow the instructions to activate it.
4 - Your game is now viewable in the “Library” tab and is available to download/install when you’re ready