"Planescape: Torment is a computer role-playing game developed for Windows by Black Isle Studios and released on December 12, 1999 by Interplay Entertainment. It takes place in Planescape, an Advanced Dungeons & Dragons (AD&D) fantasy campaign setting. The game's engine is a modified version of the Infinity Engine, which was also used for BioWare's Baldur's Gate, a previous AD&D game set in the Forgotten Realms.
Planescape: Torment is primarily story-driven; combat is given less prominence than in most contemporary role-playing games. The protagonist, known as The Nameless One, is an immortal who has lived many lives but has forgotten all about them, even forgetting his own name. The game focuses on his journey throughout the city of Sigil and other planes to reclaim his memories of these previous lives. Several characters in the game may join The Nameless One on his journey, and most of these characters have encountered him in the past.
The game was not a significant commercial success but received widespread critical praise and has since become a cult classic. It was lauded for its immersive dialogue, for the dark and relatively obscure Planescape setting, and for the protagonist's unique persona, which shirked many characteristics of traditional role-playing games. It was considered by many video game journalists to be the best role-playing game (RPG) of 1999, and continues to receive attention long after its release."
Source: Wikipedia, "Planescape:_Torment," available under the CC-BY-SA License.