97th Puzzle Piece

There is a bonus puzzle piece in Darkest 1-4.
Solve the Dracula's Castle Crypt room to unlock Darkest 1-4.
Now, <Esc> Options and set your Brightness to 2.00. (Not required to get the piece, but it will help).
Touch the Obelisk and start / restart Dracula's Castle puzzle 4.
Approach the puzzle. Directly above the puzzle is a sconce (torch). Flip it so it's pointing down.
EDITORS NOTE: Just tried this by restarting and not flipping the sconce and could still see the puzzle piece, so this step might not be necessary...
Assuming facing the puzzle is N and the Obelisk is South of you...
Turn to your right (East) and walk towards the SE corner of the puzzle (past the 2 men with the key / 4 apples under a tree / man with apple on his head portraits), and turn North at the right most pillar so you are walking towards the dark back of the puzzle, hugging the wall to your left.
Just before going beyond the puzzle, you will see a corner (with some light mist). The puzzle piece is halfway down on the East facing side of the building.
Pick it up and return to the lobby for your well earned trophy.