Ragnarok

[Gandwarf]

Yeah, if the Gods fought it out on the world I would expect entire continents blasted to ash, giant craters, vulcanoes, etc. There might still be lingering effects, natural like the climate being totally messed up, to unnatural (for example: step into this desert over here and hey, suddenly you get burnt to ashes because of some lingering spell or power - or ancient demons or mechanical constructions, leftovers of the great war). There could be a new ice age or an immense drought. Coastal areas or entire lands might be flooded. New land might have risen above the sea, bringing with it ancient ruins and legends.

Anyway, a war on that scale would probably mean a lot of humanity is scattered. Nations would cease to exist and people would band together in tribes. Food would be scarce as farmlands, cattle and other animals would be rare. There might be cannibalism and slavery. Lots of people would prey on each other, but there might be some people trying to start over in small communities. Smart traders would be able to make a fortune, although money might no longer function. Disease might run rampant.

There still might be a few (battered/besieged?) bastions of civilization, maybe that's where the people who want to ascend to godhood are mostly located. Probably not all them would be nice and maybe there's sacrifice and blood offerings going on. New cults and religions might appear, mostly dark in nature.

Then you might still have some of the old gods, diminished in power, maybe banished to the earth, who resent the fact that there are people trying to be new gods.

Should be a cool setting for a story/maps