A role playing game developed by Black-Isle, the same bunch of folks responsible for Baldur's Gate and the soon to be released Icewind Dale. Based on the Planescape franchise from TSR. Much like all of the games previously mentioned, Torment uses the Infinity Engine developed by BioWare.
In this game you take on the role of The Nameless One, who is a dead guy. No, he really is dead. You wake up on a table in a giant mortuary, and you are dead, and someone has carved a message into your back. The game has a really vivid storyline and dialoge between characters. For Example, when examining an enemy skeleton, instead of saying "this is a skeleton", the enemy would be described as "a wretched looking skeleton that reeks of decaying flesh. Straps of leather are fastened and bolted into it's bones to mimmic the function of tendons and muscles."
You also get to meet a unique group of beings in your group of characters. My favorite is Morte, a disembodied wise-cracking skull, that attacks enemies by bitting them.
I have not yet finnished this game, but my first impressions are really good. Highly reccomemded if you like AD&D/fantasy based games.
Other Planescape Torment Goodies
The Nameless One
Holy Flamin Frost-Brand etc...
Rubikon Dungeon Construction Project