Wasn't sure where to put this and I'd like to hear what you guys all think.
A huge plot bunny just thumped me in the head, and it's name is reverse-punk. (working backwards from modern technology into old)
Summary: All things needing electricity or fuel suddenly stops working, especially if it is a weapon. So humanity has to resort to making old fashioned weapons with new materials. New ways of powering things needs to be found, like perpetual motion mechanisms, man powered or clockwork, though trying to stay away from steam punk-ish things, then again nothing can be steam powered anymore.
Idea floating around in my head:
September 1st 2020, across a war torn globe, after a break out all across the continents and the seas something spectacular and terrifying brought humanity to a grinding halt. The sun did not rise, scientists are baffled, all creeds of religion had no answer despite trying to find one. Astronauts are just as confused, unable to see the sun from the stations and unable to return home. The planet below is bathed in inky blackness, and no one knows why. The fighting stopped only briefly and then the panic began. People blamed others and soon the war began again, every last country fought against enemies and allies, destroying anything that looked remotely hostile.
2040 the fighting has stopped again, there's no more fuel for the machines, no more power, and sea levels are dropping as thick clouds build up in the sky. It is as if the planet just stopped. Of course some clever buggers went underground and made their own fuel but it was nothing like the old way. It powered machines small enough for farming but the minute someone had an idea to weaponize it, it stopped. So those who wished to keep fighting resorted to ancient technology, swords were cut from scraps, bows made from salvaged pvs and arrows or anything that could be launched from it.
People rarely leave their sheltered lands, since the world around them had become hostile. Trees no longer grew up but out, as did everything else that once reached for the sunlight.