The story of Twin Sector takes place in a post-apocalyptic future where the remains of mankind have been put to artificial sleep in cryogenic chambers deep under the contaminated surface of earth — until the planet becomes habitable again. You as the player must take the role of Ashley Simms, the protagonist of Twin Sector.
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