At the dawn of the 22nd century, the conquest of space and the colonization of the solar system is being monopolized by several huge and ambitious mega-corporations. Although extremely delicate and vulnerable, a balance is maintained by these companies.
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