The vast abandoned cityscape between the Over City's safe villages, where the floor's monsters roam.
The Over City Ruins are the wide swaths of decrepit, fog-shrouded, moss-covered abandoned city that fill the Over City between its hundreds of scattered villages, all connected across a floor roughly the size of Arizona (~300,000 sq km). Per the floor's children's-story backstory (a tale never told on Earth), the whole level sits inside a dormant volcano's crater: a magical six-layered world where a great monster at the bottom breathed poison gas that killed or transformed ninety percent of its people — the survivors' descendants staff the villages, and the transformed became the monsters haunting the ruins. Monsters roam the ruins day and night, growing far more dangerous after dark.
Saferooms and restrooms are scattered through the ruins as before, but tutorial guilds exist only in villages. Carl, Princess Donut, and Mongo left the first small village through a waist-high gate to grind their way east toward a larger settlement.
Crumbling, moss-covered brick buildings slumping in on themselves, overgrown abandoned parks, rolling fog obscuring faint structures of all shapes and sizes; a false ceiling-sky of a blazing red sun by day and darkness by night.
The floor-three wilderness the party must survive and traverse between safe villages.