I figured I would write this follow-up post after talking about Linux. Follow the instructions from 2 x 2 Games to install on Linux (basically unzip and copy over to a folder). However, one mistake they made was having you copy the DLCs into the Unity of Command folder. DLCs actually need to go into the DLC folder under the Unity of Command folder to be recognized by the game. When the DLCs are installed correctly and you start the game, you will be asked for your key code.
I also had trouble getting the sound to work. Read the readme file for help. I am using a Dell Optiplex 780’s built-in sound. The sound works fine with other games so I know the sound is not the problem. The music isn’t that exciting in the game and is repetitive so no great loss. The game still plays great.