Planescape: Torment

Sigil... A place with gates that lead anywhere in existence, provided you have the proper key. It is a neutral ground and a watering hole for races across the multiverse, all under the watchful shadow of the Lady of Pain, the enigmatic ruler of the city. It is a place where the word is mightier than the sword, where thought defines reality, where belief has the power to reshape worlds and change the laws of physics...

But there's a lot more out there than just Sigil. Get outside the city and there's the planes themselves: the throne of the gods, the battleground of the eternal Blood War, and home to more horrors and wonders than ever existed on any Prime Material World. There's enough crusades, exploits, treasures and mysteries to keep a band of adventurers busy for centuries to come.