The world's land was submerged, and survivors relied on garbage and debris piled up to form "floating islands" to survive. The water is grey-green, visibility is low, and beneath the water are the ruins of sunken cities.
Scarce resources: fresh water (needs to collect rainwater or distilled seawater), soil (cannot be regenerated, only exists at the bottom of a few floating islands), plants (regarded as sacred objects, one weed can exchange for a week's food).
