All of these games somewhat fail in the sense that a war against NK and America wouldn't involve a land invasion of NK in America, that would almost be suicidal.
The most that would occur is a ton of bombing of the island including South Korea.
This also assumes that China is on NK's side since they wouldn't get past the "bombing SK" stage without them
North Korea isn't as convenient of a villain for a video game as Russia or China in the sense that your military is in general way better equipped and better supplied. It's why all of the games that use this concept always set it in the future where NK becomes a Russia/China style superpower.