If you do not have a Steam account, you will need to download the client from the official website, install it and then create your account. Once you are logged into your account, click on "Add game" in the bottom left corner and then on "Activate product on Steam". After a few clicks on "Next", you can finally enter your CD key, the game will automatically be added to your library and the download will begin.
Use your activation code to download the game from EA App.
Crysis
If you do not have an account with EA app (formerly Origin), you can download the client from the official Electronic Arts website and install it on your computer. When the installation is complete, follow the on-screen instructions to create an account. Then go to the "My Game" tab in the EA app client and click "Add Game" at the top of the page. When you enter your activation code, you will finally be able to download your game, which will automatically be added to your game library.
CD key to use on the GOG GALAXY client to download your game.
Crysis
To activate a game you download on GOG Galaxy, open the application on your computer, log in to your account, click on the menu icon, and then select "Game Codes". Enter the game code in the appropriate field and click "Continue". Once the code is verified, the game will automatically be added to your GOG Galaxy library where you can download and play it.
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