1. Download the Steam client from the official website — http://store.steampowered.com/about/
2. Install the Steam client (if not already installed)
3. Log in to your account using the provided data
4. Download the game files
5. Disable the possibility of broadcasting
6. Disable cloud saving
7. Start the game online for 1 minute, and then exit.
8. Enter offline mode
9. You can play!