The Haunted Halloween seasonal event is available from October 27 to November 2 each year. The event can be enabled (or disabled) from the main menu.

During the event, the castle is littered with Halloween themed decorations. There are two Halloween achievements. One for extinguishing all 18 blue pumpkins scattered around everywhere, and the other for solving the puzzle door to Pumpkin Lord's Tomb.

It's recommended you finish the main game first so you have full access to the castle (and its secret areas) before going for these achievements.

Extinguish all of the blue Jack-'o-Lanterns during the Haunted Halloween seasonal event.

1. Exit the castle and cross the wooden bridge. This can only be found by accessing this area from the castle side.

2. In the caged area across from the blue generator.


3. In a cabinet in the storage room. There was a lever handle here in the main game.

4. In the caged area, on right of the puzzle box.

5. Go upstairs and enter the office. Turn around to find it under the table.

6. Return downstairs and go through the green door. Turn around and look above you.

7. Enter the kitchen. Turn around and look up at the cross beam above the arch you entered through.


8. Go upstairs to the second room of this area. Look around to spot it on top of a bookshelf.

9. In the hallway connecting the bedrooms - it's by the table with the sheath.

10. In the attic accessed through the bathroom - spot the pumpkin high up on a beam.

11. On top of a cabinet in the studio bedroom, hidden from plain sight. I believe there was a photo up here.

12. In the secret area behind the TV in the master bathroom.


13. Downstairs in the cellar. A skeleton is holding this one.

14. Crawl through the grate by the previous skeleton to the Mountain Bräu Brewery. The pumpkin is on a barrel.

15. Enter through the secret panel beside the thermometer puzzle.

16. On one of the busts in the bust hallway.

17. Go downstairs in the stone spiral staircase. Turn around and look up the way you came.


18. Look up at the light in the first room.

Find a way into the Pumpkin Lord's Tomb during the Haunted Halloween seasonal event.

There are four gargoyle statues (one in each chapter) that serve as hints to unlocking the door to Pumpkin Lord's Tomb. Each statue has a skull that will change its eyes when turned to a particular direction. I'm not sure if visiting these hints and rotating the skulls is necessary, maybe the door will unlock with the right code whether or not you mess with the statues.

The statues are found in the following locations:
Chapter 1 - in the secret area beyond the caged area in the main foyer.


Chapter 2 - Lady Catherine's secret room. Go to the hidden area behind the bookcase in the reading area and then through loose brick wall.


Chapter 3 - In the cellars, through the second set of grates (not brewery ones).


Epilogue - Top of the tower.


Summary:
Statue 1 - skull has both eyes lit up when pointed east
Statue 2 - skull has the right eye lit up when pointed north
Statue 3 - skull has the left eye lit up when pointed northeast
Statue 4 - skull has neither eye lit up when pointed northwest

With all the hints in hand, return to your boat (still remember it?) to find the tomb.


Go up to the door and rotate the four skulls according to the statue hints.


Enter the tomb to the achievement!