[post in this thread] one-sentence setting/world/culture idea bank

[Exegesis]

Demons have granted the world's ignorant children sovereignty over all things, and their deposed parents struggle in the dark for a way to reclaim it.

The ocean has been drawn into vast extradimensional reservoirs and the people, who now dwell in the endless arid arenas that sprawl between the shelves of the world, trade for meagre helpings of that liquid with countless and ever more debasing favours.

The curse of God has mutated the first language into a thousand disparate forms so that the clans of the peerless tower Babel, which is near the end of its construction, neither trust nor comprehend one another.

[Seraphine_Harmonium]

Angels and Demons wage a war, using earth as their battleground.

Thousands of random people suddenly acquire super-powers, most of whom will have no idea what to do with them, or how to control them.

A town ravaged by outlaws and savages will hire as Sheriff anyone who will take the job, no questions asked.

When a magically rich fluid is discovered in a peaceful settlement, several powerful mages descend on the town to battle it out for the arcane resources present, with no regard for the collateral damage.

A town where the ghosts of departed relatives never move on, but instead form an ever larger community of spirits that demand to be treated as though they were still alive, taking a share of the food, and a seat at the table.

[Exegesis]

The Great War spawned a thousand-thousand instruments of horror and now those devices have formed tribes wherein the greatest machines – fuming anthropoid nuclear beasts and supertanks whose treads span miles – are chieftains and dream of empires to match the mightiest of humankind.

King-of-heaven, whose form is divided among a billion stars, split the dominion of the lower sky between his two sons Saul and Lund to prevent a war of succession, but all gods are greedy and the war came regardless so that the sky is eternally divided and half the world is burned black while the other half is as pale and as cold as the hearts of demons.

The Emperor captured all of the new religion's saints and hanged them along the highways of his empire, but their god has blessed (or cursed them) to continue their ministry and now they are deathless and possessed of altogether different miracles.

Seraphine_Harmonium

A land where status is determined by generosity, such that the poorest of the poor are chosen to rule, only for them to abdicate their rule to somebody else immediately, to prove how fit they are to rule.

I like this one.