The ultimate thief is back! Tread softly as you make your way through 15 new complex, non-linear levels full of loot to steal and guards to outsmart. Improved enemy AI, new gadgets and a riveting story will draw you into the world of Thief II: The Metal Age, a place of powerful new technologies, fanatical religions and corruption.Go to: http://store.steampowered.com/ and download STEAM client
Click “Install Steam” (from the upper right corner)
Install and start application, login with your Account name and Password (create one if you don’t have).
Please follow these instructions to activate a new retail purchase on Steam:
Launch Steam and log into your Steam account.
Click the Games Menu.
Choose Activate a Product on Steam…
Follow the onscreen instructions to complete the process.
After successful code verification go to the “MY GAMES” tab and start downloading.