1) Disable Windows updates (If you have Windows 10, disable updates using the program https://goo.gl/G4F6BO )
2) Install the Steam client https://store.steampowered.com/about/
Important in Steam settings, uncheck the launch with the PC! (If you already have Steam installed, then you need to install another Steam2 in a separate folder).
3) Copy the Activator.DN and Steamoffline files to the root of the Steam folder. (A link to them will be given after the purchase)
4) Run Activator.DN (on behalf of the administrator), enter the ID received during the purchase.
5) Wait until the utility checks the key and enters the account, do not touch anything (login / password is automatically entered)
6) Download the game.
7) Go into the game, to the main menu. You do not need to start a NEW GAME (go to the settings and play will be AFTER activation).
8) Immediately exit the game menu and press the exit button with Steam.
9) Activation completed. All subsequent launches of the game strictly through the Steamoffline file (for convenience, you can make a shortcut on your desktop, it will launch steam by default and immediately play the game offline.