Sid Meier's Civilization V - Cradle of Civilization: Mesopotamia

Steam

1. Start Steam on your computer and sign in to the account you will play on.
2. In the Games menu, choose Activate a Product on Steam. You can also start from Add a Game at the bottom left.
3. Go through the introductory screens, review Steam’s terms and paste the complete key without surrounding spaces.
4. Finish activation, then find the game in your Library and select Install.