Installation method: download the file "The beginning of the end" and unzip it twice. Place the campaign file in the "UserCampaigns" folder, which is located in the game's folder. In the game itself, select single-player mode, then Modifications, then Load, select "The beginning of the end" from the list, and load it. After that, you can launch it as a regular campaign.

(Note) The first map has been remade. Now there are no glitches when loading saves. Make sure your video settings are higher than the minimum so that all objects on the map are displayed in the game. Good luck in your battles!