Trivia
One easter egg I remember from this game is that when your PC clock/calendar read 25 Dec, a Christmas tree appeared in the great hall of the castle.
The game featured digital sounds with the PC Speaker. However, the PC version sounded way inferior to the Mac version which initially convinced me to buy this game. (Editor's Note: Hey, at least the PC version was in color ;-)
There was a Dark Castle and Beyond Dark Castle t-shirt and sweatshirt offer that came with the game. However, I doubt it's still valid. :-)