WMG: Sora No Woto
The fate of the world arose from a series of Colony Drops from an alternate series of events in Franchise/Gundam.The events from Mobile Suit Gundam: Char's Counterattack have gone bad, and multiple colonies were dropped after a long, brutal war, destroying much of the planet's biosphere.
Amazing Freaking Grace is more than just a pretty hymn for Helvetians and Romans.The fact that the Takemicaduchi had a copy of it and it being universal enough that both Romans and Helvetians over-react upon hearing it might point to Amazing Freaking Grace having a powerful historical significance. Take into account the Culture Chop Suey, and you can have an scenario where Humankind united against "Them" and mobilized all over the world to face the enemy globally, using Amazing Freaking Grace as their battle hymn. When the world went to crap, the mobilized armies were stranded on the spot they were last defending and settled down there. Amazing Freaking Grace was for the survivors of this war a symbol of hope and unity in the face of annihilation.
Sora no Woto is the same universe as Spice and Wolf.
- In the after-series filler episode, Yumina (the nun) tells Kanata in conversation that she (Yumina) is the daughter of a traveling merchant who goes around the countryside in a horse and cart. Mother is mentioned as just being absent.
- It's possible that other parts of the world may have even regressed further into Medieval-like conditions. So it's not that far-off an idea.
The Time Telling Fortress is Antarctica.
- The garrison consists of two naive rookies, a royal bastard whose presence is, until story's end, a political embarrassment, and two shell shocked vets. This is the place the military sends people they don't want near anything important. It has enough value to necessitate some military presence, but not enough for a substantial one (since I doubt anyone contemplated an attack over No Man's Land). So they send soldiers who would be liabilities in normal circumstances, but for some reason are important enough that they can't dismiss entirely, to the place.
- The humans put up a valiant fight, and eventually develop their own advanced weaponry to fight the aliens, but they ultimately lose and are forced to retreat into the small pocket of land the current nations are located in. The aliens eventually leave after they've drained the majority of Earth's water, which is what caused most of the planet to become No Man's Land.
Angels destroying the world?
It's a prequel to Now and Then, Here and There.
"Them" were Bird Men.
- Think of Sora No Woto as an alternative follow-up to Macross Zero where the Bird Man came back with friends to annihilate Mankind. Too bad there isn't a Love Triangle...
The world is a prequel to the world we see in Nausicaa of the Valley Of the Winds.
- The world is devastated and poisoned. No fish in the sea, it's becoming sand, and the little pocket kingdom of Seize has a very similar feel to Nausicaa's home. It also could be that the "Them" that destroyed the world are the biological monstrosities found in Nausicaa, and were distorted yet again in legend into being something they weren't.
- But in Sora no Woto the uninhabitable areas are just deserts, not some poisonous freaky jungles with weird-ass deadly creatures in them.
Sora No Woto is set in a world where the Axis won World War II
- Which explains why the girls are wearing Wehrmacht uniforms and the tanks are absolutely gigantic like the Nazi plans for the Maus and the Rattes. The Japanese and the Nazis probably had a war against each other and the surviving Japanese got deported to Switzerland explaining the hybrid culture. Switzerland incidentally probably lost most of its German-speaking cantons due to the Third Reich wanting to incorporate all ethnic Germans which is why Helevetia speaks primarily French and Japanese even though in the real world, Switzerland has far more German-speakers than French-speakers while Rome is obviously a descendent of Mussolini's regime.
- HOLY SHIT, how did Those Wacky Nazis fuck up the planet that badly?!
Rio assumed she would die in seeing her dream through.
- At least until Kanata decided she would stay by her side. Traveling a world-devouring desert alone countless miles from civilization, using an extinct method of transportation nobody in the era knows anything about? Going "beyond the ends of the earth" in search of some mythical sea based on something her mother mentioned once? It's basically a Tragic Dream. At the very least, she was Not Afraid to Die to accomplish her dream, even if she perished far from civilization without sharing what she found on her journey, and nobody ever heard from her again.