Point is: what is the invasion. If he didn't change too much about the people life, then why fighting? To endanger your family? Give the occupation forces reason to attack civil people instead of just be an army fighting another army?
Because that what this kind of behavior will lead to. If some civil take the arms to fight back other army, then the other army will for sure attack the population, something that could maybe have been avoid.
But we must first concentrate ourselves on the way to entertain people, for video games to live. Else, it's a world where sales representative will win, which has as effect to kill creativity. I want to say to the creators all around the world:"Courage, Dare!". Shigeru Miyamoto.