Please Darksiders (Warmastered Edition) Steam Key Game Activation: 1. Open Steam 2. Click on the Games menu 3. Select Activate a Product on Steam 4. Enter the serial key and click Continue, then follow the on-screen instructions (Please type the Code manually or copy-paste it). After that, the game will automatically be added to your library and can be downloaded directly. Once the download is complete, the game can be played immediately. The game will be available in your Library.