Ultima Underworld: The Stygian Abyss

Ultima Underworld is set in Britannia, in the aftermath of Ultima VI: The False Prophet. The game takes place entirely inside the Great Stygian Abyss — a vast underground dungeon on the Isle of the Avatar, whose depths once housed an ambitious experiment. A man named Cabirus tried to build a ninth virtue-settlement there, uniting humans, goblins, trolls, and other races in a colony devoted to all eight of Britannia's virtues. He died before distributing the magical artifacts meant to bind the colony together, and without that foundation it collapsed into war. At the time of the game, the Abyss holds the fractured remnants of that failure. The story begins with a trap set by the sorcerer Tyball, who betrayed his brother Garamon to a demon called the Slasher of Veils, hoping to gain power — only for the demon to be partially sealed when Garamon's death imbued the containment room with unexpected virtue. Tyball now plans to sacrifice Baron Almric's daughter Arial to break the seal. The Avatar arrives just in time to witness Arial's kidnapping, gets caught by the Baron's guards, and is banished into the Abyss to bring her back. The journey through Cabirus's ruined colony is the game itself: navigating goblin wars, learning ancient languages, solving the puzzles left by a civilization that failed. At the bottom waits Tyball, and beyond him, the demon that started it all.