I was going to post a Dak'kon quote, but I couldn't. Instead, I'll describe how Planescape: Torment made me feel:
Have you ever woken up, as you did the day before, and the day before that; to feel that despite the world you have created, your life is empty. There is something missing. There are questions so unaswerable they make you fear their asking, to the point where the oblivion of sleep seems more real than what's become your reality.
I'm no child of Bhaal, no half-elven ranger, no dwarven mercenary. I'm lost in a world void of meaning, where actions have no consequence for their indulgent accessibility. I'm not interested in death, or acting out some fantastical reality, all I'm interested in is me, and making sense of a world which becomes more and more alien.
This game changed my life, and I often think of it. Don't play it as a game, play it as an experience.