That sounds about right thinking, if u want impossible to beat a.i. I'm sure u can make it, but does it make the game more fun.
Protecting the workers with soldiers seems like a fun way the computer can play, then you make the computer target the workers of the other side, and take out the soldiers in the way, then theres some balance of forces, you should only strike when u have the upper hand. That sounds like the basic way to do it.
