This game is a strange one. The strongest thing it has going for is it's brilliant game design. The graphics are fine (prone to a little CGI-ish cutscenes, but those are sparse anyway), the sound good (the characters would only speak the first couple of lines and then the rest was text), and the fighting system OK I guess. But what I found here was something that has proven me wrong (and only once, I must add); that there can be such a thing as interactive storytelling.
I am someone who has dedicated their lives to the understanding of narrative across media and have always been drawn to the mythological weight that narrative has. I've always cast a skeptical eye on every age's admonishment that the old grand narratives have crumbled and that a new modern age of storytelling is underway. Bull. Narrative is a method of conveying mythology (and by mythology I mean a package of culture, morals, and story. Much like what George Lucas did with the first Star Wars trilogy) and it can never be a thing of the past.
However, Planescape manages (mainly through text driven narrative) to open up the story to people. Basically the system is the same as Baldur's Gate; you command a party (albeit a party of freaks), move them about, fight monsters and occasionally use things in your inventory with things in the game's world. The meat of the game is in the dialogue box that opens up everytime you look or talk to someone.
It pretty much takes up half the screen, but is laden with equisite description that takes over from the isometric graphics in visualizing the game. Characters go through swaths of dialogue and the options are plenty, each slightly altering the course of the game.
Adding to the twists in the game, the universe it takes place in is a brilliant one. As a D&D player I pounced on the Planescape boxed set when it came out. It provided hours of reading, for the Planescape world exists in a land shaped by belief. Somewhat akin to Alan Moore's concept of Ideaspace, Planescape is mapping out of the ethereal world beyond. In it the dead mix with living, ghosts, demons, gods, concepts, monsters - basically anything that can be thought of. It also personifies all the alignments of D&D and paints them out in their respective worlds; for example. chaotic evil a land forever locked in a battle between two demon races called the Blood War. Sadly, it seemed that for all its intricate beauty, the boxed set was one of those unplayable D&D accessories due to all its weird rules.
However, Torment takes all of the madness and lays it out coherently into one of the most splendidly interesting environments you could dream up. You will find yourself helping a street give birth to an alley so that you can make it to the other side of the Hive, at one point!
Central to it all is poetically sad story of your Nameless protagonist. Taking Plato's notion of life (that it is spent "remembering" flashes of the all that we once knew) Torment's gameplay allows your character to shift between classes, let alone morality. At it it's core, the story is one of self-discovery; just why are you immortal? Why are you covered in runes? Why will people follow you beyond the veil of death? The answers are bigger than you could possibly imagine.
To this day I remember the end of the game; pathetically sobbing alone at 4 in am whilst the Nameless One unravels the mystery, wishing this perfect end was not the end. No game has moved me like this. But believe me, if you appreciate a good (great) story and are willing to commit to reading a lot to get to it, this one is must play. The best play.