The Stellaris dome set is a thematic set of visual skins for the Martian domes with a futuristic design and star-shaped elements. It is available for the following domes:
Basic Dome: A small dome, suitable for the early days of the colony.
Medium Dome: A medium-sized dome design.
Oval Dome: An elongated dome design, which has space for two Spires.
Mega Dome: The most advanced and spacious dome design.
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