Empire of Ys is a roleplaying game of worlds-spanning fantasy. The rules are built up from an Old School core based on loosely on the world’s first fantasy roleplaying game, but heavily tailored to fit the setting.
At the centre is the city of Ys, a corrupt and baroque fantasy city occupying a folded dimension of its own. Magical gateways created by the Guild of the Arcane link Ys to other worlds. On some these worlds the city has set up permanent colonies. Ysian raiders, traders and explorers reach further afield. The heart of Ys is rotten. Its overlord, the Autarch, is literally a monster. His immediate underlings, his Agents, sow discord in the city, and can hunt and feed on the city’s less prominent citizens with no fear of punishment. He leaves the apparatus of government and the rule of law to crumble and divides the power structures in the city among conflicted guilds, ensuring that no-one can depose him.
Doesn't sound too much like the actual legendary city of Ys, but something more out of Michael Moorcock.