I feel the need to chime in, since my good friend is about to start up a PBEM based on the excellent novel The Windup Girl.
First, why look to international crisis as the reason for the end of days? Nature can provide a much more interesting scenario, without any of that messy geopolitical reasoning mumbo jumbo. Global warming, famine, disease, energy and water crises. And why is China inherently evil in your timeline, any way?
Now, in that global situation, multinational agricultural corporations might save the day with GM crops resistant to crop failure / stem rust / whatever else. These corporations (since there probably wouldn't be air planes flying everywhere) would rely on dirigibles and the reuse of sea routes. There, you have the establishment of a new type of economic means (somewhat) -- and also international intrigue (perhaps one corporation intentionally releases stem rust, knowing it will eradicate another country's food supply, only to come in and tout their own product; while sovereign nations maintain a "seed bank" or some ultra-powerful agricultural department, maintaining original, rare, non-GM seeds and lucrative, delicious crops). Since I think you want a little bit of campy, pulp sci-fi thrown in, you could say that a new energy source (given the energy crisis and peak oil) is kinetic energy. What can generate large amounts of kinetic energy? Well, genetically-modified slave creatures, like massive mammoths or other remarkably powerful creatures. If you want to really make it pulpy, have some escape and cause havoc somewhere.
And don't forget genocide. If there are food, water, and energy crises, the first groups to be exterminated will be minority groups, or groups that had, at any point in time, been discriminated in the modern era (maybe the Chinese population in Malaysia, or the Korean population in Japan, for some examples). This could cause all kinds of other interesting scenarios and world-shattering situations.
So in the end, you have a post-crises-genetic-creature-roaming-kinetic-biopunk-madhouse sort of NES. Maybe due to chem weapons or nuclear reactor failure, you can have some fallout areas, and certainly due to overheating of the earth and famine, you can have other sorts of inhabitable areas. I won't be playing, but just thought I'd throw some stuff at you.
Oh, and you should start in the 2200s or 2300s. 2099 is too soon.