This has me curious.
So if Half life 1 was world war 1 and then just as people were getting a bit down along came the second to kick it all off again.
Even the US civil war thing (world war 1 was probably the first modern war but the little discussed, outside the US anyway and certainly at the time of WW1, US civil war was definitely a example of things to come) works when we consider Half life was something of a retooled quake engine.
The episodes would be something else, the question is whether it is Korea and Vietnam or the various Gulf and middle east stuff. I will also have to figure out where the likes of blue shift come in, I am thinking Russia, China and Spain with their civil wars.
The question is then are we now living in the cold war where you get a few proxy wars (like Left 4 dead) or are we past that? Counterstrike clearly reflects the increased amount of special operations and spies running around where Team Fortress represents the wars for resources, though ones where the money of note tends to end up in the hands of those with the means to get them together.