You are a God! You are master and ruler of a loyal nation. You have unimaginable powers at your disposal. You have claimed this world as yours. But there are others who stand in your way. You must defeat and destroy these pretenders. Only then can you ascend to godhood and become the new Pantokrator.
Open the Steam client, login and locate the Games tab on the top menu. Click this and then select “Activate a Product on Steam…”
Enter your unique code that's displayed on the 'Orders' page of CDKeys.com and follow the prompts to activate.
Your game is now viewable in the “Library” tab and is available to download/install when you’re ready. You can find additional support for the Steam client here: https://help.steampowered.com/en/wizard/HelpWithSteam