July 15, 2025 8:47 PM (GMT+2) This is a catch-all mystery for everything related to the underground. Right now I have many pieces of evidence and mysteries that I cannot fully connect and I’m starting to lose track of them. The underground seems to have become very relevant due to the note I found in the Antechamber: “To continue up, you must go down”.

My main idea of how to keep progressing is by getting across the Reservoir by using the boat (see Can you get across the Reservoir (using the boat)?). This would allow me (I think?) to get to the other side of the minecart (see Note about minecarts).

Another idea is to access the Rotating gear room from the Blackbridge Grotto. This is speculation, but I think if I can open the door, it will lead there (see How to open door at Blackbridge grotto?).

Apart from that, there is the “foundation elevator” which would be seen on the Underground map, but I’m missing that corner. The document About the foundation elevator talks about it. It seems likely to me that it is related to the “continue up” part of the Antechamber note.

July 16, 2025 3:07 AM (GMT+2) I also realized there’s some candles that I can for sure light up, and surely something will happen, see Candles in the abandoned mine.

July 19, 2025 11:41 PM (GMT+2) I drafted The Foundation. Turns out it was just a rare room within the manor. I also could apply the knowledge from About the foundation elevator to activate the elevator and rode it down. There, I found two things:

• A button with a keycard slot that lets you call the elevator
• A door that requires the basement key to open it

Sadly, I could not reach the Antechamber that day to see what’s past that door, but surely it must connect to the missing corner of the underground area (potentially at the other side of the Reservoir?).

July 24, 2025 1:45 AM (GMT+2) I somehow solved everything on a single run. I got the Underground map, opened up all shortcuts and basically explored the entirety of the underground. The main point of it all was to access the North door lever to unlock the The 46th room. There’s still some mysteries left, but I don’t think it’s worth it anymore to keep this one open, so I’ll mark it as solved.