Betrayal Mode lets you completely reverse the usual game flow, working as a full planetary power trying to destroy your foes, not unite them. Invasion Mode sees you working with the other races to survive slaughter by a grave new threat. Plus new ships, abilities, music, and more!
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