A virtual fence surrounding the castle that prevents the player from accidentally leaving the compound.

It should be activated after the player is brief via "phonecall" from the game start flag and would last until the final puzzle is completed. After the final puzzle is completed, this fence also acts as the trigger for the alternate ending where the player tries to escape without following the instructions from the phonecall.

While the game is going on, entering this zone and remaining for more than 10 seconds would trigger a "phonecall" reminding the player of the objective and telling them to return to the castle.