It's actually quite hard to do something like that. Human resistance movement is a good one, and will probably be part of the solution. Although the game needs more diversity. There are gonna be weapons for example, which do (let's say) lightning damage. or firedamage. or projectile damage. Some of the enimies need to be i.e. imune to fire but extra vulnerable to lightning. It's hard to explain all that with armortypes only...
The players are playing 'the bad guys' so to say, like the dark force in starwars. So they would even kill, if it is not neccessary. The whole story is about to be written. If you have any more thoughts on that, please lemme know.