Some personal works for Punk city concept.
An unknown Soup-sea flows in, and destruction begins.
The sea, assimilating everything, encroaches on living spaces, leaving the world with only highlands like islands.
The survivors expanded vertically to expand their living spaces. While most remained shabby and undeveloped, a few successfully rebuilt megacities emerged.
As the city developed, a natural hierarchy developed.
Most citizens live in the lower-class districts, unmined and threatened by the sea, under the surveillance of a tiny upper class.
Class polarization is the city's detonator. The volatile discontent of the lower classes is quelled through various means of surveillance, appeasement, division, and desensitization.
Previous technologies, nearly extinct, are partially restored and developed in a way that suits the modern era, in a direction different from what we know.
Essential resources like water and iron ore still lie beneath the unknown sea. Extracting them is a highly risky undertaking, requiring technology and scale.