Location from Undertale / Deltarune by Toby Fox
The world beneath Mount Ebott — a vast cavern system where monsters were sealed after losing the war with humanity, and where every step forward is a choice between mercy and violence.
The Underground is both a prison and a home. Monsters were sealed here after the Human-Monster War, trapped behind a Barrier that requires seven human SOULs to break. Despite this, they built a civilization — towns, schools, shops, a monarchy, a TV station, a spider bake sale. The Underground is cozy and claustrophobic and desperate and kind. The geography flows like a journey: the Ruins (tutorial/childhood), Snowdin (friendly hometown), Waterfall (mystery and beauty), Hotland (technology and spectacle), New Home (the final confrontation with consequence). Each area has its own color palette, its own music, its own emotional register.
A sprawling underground world of impossible variety — snowy forests, bioluminescent caves, volcanic wastelands, and a royal city, all contained within a mountain. The architecture shifts from ancient ruins to modern apartments to industrial machinery. Light comes from crystals, lava, and magic. The ceiling is always there, reminding everyone they're trapped.
Also known as: Mt. Ebott, The Monster Kingdom