What is this about? ^ the title ^. A while back, walking along the dungeon minding my own business, I literally just stumbled upon this interesting discovery. As I couldn't find anything related to this with a forum search or two, I decided to create this little tutorial-ish sort of thingy. Basically, the secret rooms are just like any others, except for the facts that they only appear on DL 0 and are never adjacent to the rest of the floor. Given that there's only one of these rooms per floor (and the rooms themselves tend to be relatively small), finding them is mostly a matter of perseverance. I don't want to risk spoiling too much by revealing the actual contents of these secret rooms. However, rest assured that you will be surprised. What you find just might help with your Grand Quest of Dredmor Defeating as well. Requirements: RotDG, as there's no Mysterious Portals to enter in the first place without the DLC. Some means to destroy standard walls. Digging Ray and The Mighty Auger (from Golemancy and Werediggle Curse, respectively) are the most straightforward options, but any modded wall-destruction abilities should work fine as well. I don't recommend using explosives, though; you'd likely need a huge pile of them, and there's always the risk of self-injuries. Apart from the above, no mods are needed. Playing on NTTG mode might effectively limit the area of the map where the secret rooms appear on. Not sure about this one, though. Searching for the rooms around the abyss can take some time (depending on RNG's generosity), so be prepared to fight hordes of random spawned enemies when you return to the main part of the floor. As such, it's not advised to attempt this with too low-leveled a character.
Nothing is limited to the mysterious dimension only; a simple look through rooms.xml will prove that. That floor merely takes rooms that spawn from floors 1-15 and puts them together. The two secret rooms that house Diggle God of Secrets can be found in any old floors 11-15, the statue itself is just hidden.
I stumbled upon the Diggle God of Secrets by accident using a Unholy Warcry. It blew my mind. At the time I didn't even know destructible walls existed in the game, and that god had no entry in dredmorwiki.com. It really felt like a fantastic discovery. I had no idea about hidden rooms in level 0. I will definitely have to take a look!