X-Tension is the eagerly awaited expansion pack to X: Beyond the Frontier. The expansion is not limited by a linear plot line but makes use of new ways to expand your empire. You can now take part in missions that are offered to you throughout the game.
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