First pic is 100% map, second pic is my 99.9%. Apparently I'm missing one room but I've stared at these for a half hour and can't find what I'm missing. Anyone want to take a shot?
https://dl.dropboxusercontent.com/u/433791/dos100.jpg
https://dl.dropboxusercontent.com/u/.../dosingame.png
EDIT: So this is bizarre. My save file in the Abyss (after clearing the game) shows 99.9%. When I go down to the warp room below it, still shows 99.9%. As soon as I press UP to warp, it jumps to 100%, whether I jump back to the castle or stay in the Abyss. I guess I'm not missing a room, but that sure is odd.