Technically, I'm missing two rooms, but I know that one of them is the Shaft/Dracula final room in the inverted castle. That puts me to 1889 rooms. I have absolutely no idea what I'm missing. I swear I've gone over both maps several times trying to figure out what I'm missing, but this is driving me batty! Can someone out there please help me?
Here's my room count:
I know one room I'm missing is the last boss fight. I went there and beat the game and the achievement didn't pop. When I got to the room my counter was at 1889 rooms, so I know I'm missing one besides the last boos room.
If there is anyone out there kind enough to help me out, it would be much appreciated.
Nevermind, I found it. It was one room I overlooked in the normal castle. Thanks for the help, guys.