NunuXD
The next game could be Call Of Duty Ghost, the campaign is the consequences of a war in addition to a post-apocalyptic situation, this would be good since it could show the consequences of war, plus of course it has Extinction Mode and there are aliens, I think that before Loki's invasion would be a good idea, especially it will help the armies and people get used to it. But of course, you will have to provide mental protection to people so that they are not so affected by the game. Also, the people can see the things that their soldiers need to do.