Okay, this game is a masterpiece. I haven't seen many text-based games in recent years (the Crypt Shyfter series being the only one), and NONE of them have been this good.
The way that your character can evolve is great, and after the doors and the *MINDFUCK* begins, it only seems to enunciate that. The evolution of Lith is even better, as she (I played with Lith as a female) is a truly three-dimensional character. Just comparing her personality when you're being a kind master versus when she's dominating you is amazing, and she is just so adorable that it hurts!
Speaking of hurting, as the story progresses and more is revealed about her, it begins tugging at your heartstrings; when her backstory is slowly unveiled, my heart ached, and after exploring the second and third doors, it only intensified. After the fourth... I teared up. That's how good this is; the only other time I've teared up like this is over Tali at the end of the Mass Effect trilogy, and they had three whole games to implant and nurture that connection.
The story, even after the *MINDFUCK* sets in, is still engaging and well made, and still manages to remain mostly coherant (minus the third door, which seems to have its true nature shrouded). The fourth, at least in my mind, also kinda answers some of the third's raised questions, although not directly; moreso in a philosophical way, philosophical context being a major theme throughout this game.
I haven't even finished the fourth door, so I don't know if that is really the end or if there is still more to go, but all I know is that this game is full of THE FEELZ and I love it!