Pretty good shooter about Korea invading US and other countries and you rebel against them and take on the entire army.
I'm playing SP right now, and it's pretty damn good. Although I'm not liking the story as it's highly unlikely and I see a lot of discussion about it.
No, this can never happen in real life.
Oil seems to be the root of the "war" in this game. So if we were to run out of oil, the US actually has one of the largest reserves in the world and that will last us for quite a while, making all this impossible to begin with. Even if we run out, our buddies in Canada have quite a huge reserve themselves and I cannot see why they would not lend us any.
All that aside, let's say we do run out of oil and Korea does somehow unite N&S. That in itself is ridiculous. I see no reason why the South would want anything to do with the North and its enormous debt and poverty. The South cannot sustain itself AND tack on the burdens of the north.
Now let's say it somehow does and they do go to Japan and invade it. Let's stop there, the US has a huge amount of soldiers over in the Pacific guarding that region and Japan would NEVER kick us out. We ARE their army.
Okay let's give this game the benefit of the doubt and say that Japan somehow allows themselves to become slaves. So now they want us to believe that in less than a decade Korea is able to successfully annex Japan with it's already small army and THEN be able to come over to America to take over? Highly unlikely. First, most of its troops are already deployed in Japan and their army is not that vast, I doubt they'd have the numbers to come to America to take it over unless they completely abandon all posts in the Pacific, which pretty much nullifies anything they did over there. Second, there is no way they have the means (in terms of food and oil) to sustain themselves in our territory, tens of thousands of miles away to wage war against the largest army in the world. Third, and perhaps most important, if they fired a nuke at us it would never even make it here. The US has spent billions on a defense system (Project Star Wars) that would annihilate their nuke before it even gets here. Such an act would only warrant us to send our nukes to Korea, which would completely wipe them off the grid.
Oh back track a bit, I don't even know WHY we would allow the two Koreas to unite, we are damn good allies with the S. Koreans and hold strategic points over there.
So all in all, no, this would never happen.