Also TEXOKIE, They were heavy on propaganda (broadcasts from roving robotic machines and via radio) and simply walked in and took what they wanted. Survivors were considered utterly expendable. In the game, the Enclave gave the remaining ‘Americans” (In quotes as America as an entity had ceased to be) a choice. cooperate or die. Anyone considered to be tainted by mutation was subject to immediate eradication.
There are many things about that game which I am convinced the developer hired experts to research...scenarios and such. While there is a considerable sci fi element, there are many very real scenarios and scientifically, psychologically and sociologically supportable truths to be found.
Is this the “Hunger Games” book and movie series?