Some time ago I was in a conversation with Cole about Nightwick in the very pretentious way I sometimes do and the topic veered into the definition of "Dark Fantasy." It's a genre which I think there is no question that the World of Nightwick occupies, even if it's not always serious. It's also a genre which, 13 years after I first started running Nightwick still has a lot of cultural cachet. If anything it's gotten bigger in this post-Dark Souls/post-Elden Ring world, and I think for someone who works in that medium, even if it's all hack work, it's worth thinking about what it is.
Normally it is defined as "fantasy with horror elements," but very commonly Moorcock's Elric saga is included in Dark Fantasy and I wouldn't say it has horror elements. Cole provided a definition that I think does the wonderful job of including the things people would want to include and excluding what they wouldn't while also being very evocative: Dark Fantasy is fantasy that takes place in a world that is haunted.
What does it mean to be haunted? Probably at least in part because of my history background, I am going to be using "haunted" here to mean that it bears the scars of the past - a psychic shock that causes the memories of the dead to cluster there like bats in a cavern and for them to weigh as a nightmare upon the brains of the living. In thinking about this topic outside the realm of games, I have come to see history writing as a sort of ghost story. The crimes of the past have a long reach and haunt us today as much as any specter from the mind of MR James.
In our fantasy game worlds, or fantasy worlds in general, we can achieve this sense of being haunted through the numinous. The psychic scars of the past have physical and spiritual manifestations on the world. In the world of Nightwick, immediately to the northwest of Nightwick Village, is the Mire of Princes - created when the blood of an army facing the Sword Brothers so suffused the ground that it became a marsh ever after. More distantly there is the Blood Red Sea - stained that color after the demon Moloch pitched the men of ancient Acheron into it. And of course there is Nightwick Abbey itself.
Within Nightwick Abbey's hall, the sins of the Sword Brothers live on in twisted and exaggerated form. Tortures carry on forever, heedless of the death of both torturer and tortured. Hochmeisters of the past walk evermore beneath its ruins, returning again if slain for they are trapped forever. Even what was once a lavatory has taken ghastly shape in hideous memory of the room's previous purpose. Nightwick is, after all, a mythical underworld.
If you want to run something that's Dark Fantasy, as seems to still be in vogue, that's how you do it. Think about the history of the setting and how its crimes gnaw away through time into the present. It is a mode of thinking that should be easy to all of us now.
There are times when I desire to run something where the world is less numinous - a lower fantasy where heroes of maybe a Howardian stripe come to grips with monsters of super science - but then I have to write dungeon rooms. It seems my brain is either too choked by the weeds of time and the study of past wrongs or too enamored with the gothic I engaged with in entertainment and saw in the woods where I grew up. But my dungeons are always haunted. Maybe I am too.