I've never seen the Great Halls and I've no idea on any secret room. Is there a place where these locations are mentioned to the player, because I couldn't find any looking through the various patch notes.
EDIT: Also, a legitimate bug I noticed. The knockback from the Sparta cape can get monsters stuck in the walls, unable to be hit, forcing you to restart.
EDIT2: Well good news, I found the problem. I happened to have the older version (2.5) still on my computer, so I played that version and noticed a couple of really striking changes
In the current version, there are no girls chained to the walls as you move through the Prison levels.
In the current version, there is no "Moving to next floor" screen when you find the stair case, it just fades to black and puts you on the next Prison level.
In the current version, there are monsters in literally every room.
None of these are the case in the 2.5 version, which should be the 'older' version. This leads me to believe that you uploaded the wrong version.