I'm going to go ahead and ressurect this thread, because I was just struck by inspiration.
The Salvation War v Half Life
Firstly, you can find the rough drafts for TSW
here. The Salvation War is basically a what-if scenario where Armageddon occurs, and the invasion of earth by hosts of daemons begins. The twist is, however, that they are invading modern-day earth using bronze-age tactics. What ensues is a fantastic Tom Clancy novel about the invasion and occupation of both Heaven and Hell, and the stories of the humans, daemons, and angels involved in the war.
One of the biggest concepts in TSW is that heaven and hell are both pocket dimensions, a discovery which changes pretty much everything we know about physics. Portal research becomes an enormous military-civilian endeavor, and is implied to have just been breached at the end of Pantheocide.
So what would happen if the resonance cascade, as well as the portal storms and combine invasion that followed, happened to the post-pantheocide TSW universe? The Combine would be dealing with a combined-arms force of Daemons and Humans, with not-inconsiderate manipulation occurring with the Angels, and could be dealing with the very real threat of a counter-invasion.
Or the inclusion of the advancements in TSW simply delays the combine by a few days.
Either way, the idea is incredibly interesting to me. What thoughts do you bros have?