Frontlines™: Fuel of War™ is an open-world First Person Shooter set on the frontlines of tomorrow. In a world ravaged by a global energy crisis, environmental decay, and economic depression, players assume the role of an elite soldier in the Western Coalition Army on an epic crusade against the Red Star Alliance to control the last of...
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