Shadow of Yserbius

Shadow of Yserbius is a dungeon-crawling RPG released in 1992 by ImagiNation Network, Sierra's online service platform. Players choose from classes such as warrior, mage, and thief, then descend floor by floor into the cursed volcano Mount Yserbius, battling monsters, looting equipment, and solving the mysteries of ancient ruins. The game was designed from the ground up for multiplayer online play, allowing groups of players to explore cooperatively, though a fully featured single-player mode is available as well. Its oppressive underground atmosphere and deep class-and-equipment system earned it a respected place in the history of early online RPGs.