Rattus Norwegicus: A Filthy Dungeon Romp Through the Worst of Galgenbeck

There is a stairwell in Galgenbeck. It sits between two crooked buildings, unassuming, easy to miss. The locals avoid it. You probably should too.

Rattus Norwegicus is Seidmann Games’ Mörk Borg adventure, a 16-page one-shot dungeon romp written by Michael Sollien and illustrated by Nicolai Strøm.

It is, to use the technical term, filthy.

It is also one of the most pick-up-and-play modules we’ve published: tight, mean, full of tables, and over in a single session. If you’ve been looking for a Mörk Borg one-shot with teeth, this is it.

What Is Mörk Borg, and Why Do We Love It?

If you’re new to Mörk Borg, here’s the short version: it’s a Swedish doom metal album that learned how to be a tabletop RPG. Published by Ockult Örtmästare Games and Stockholm Kartell, it’s a rules-light OSR game set at the end of the world, designed to be played fast, dirty, and played with the strong expectation that your character will probably die in a horrible manner.

We love it for reasons that are hard to fully explain without sounding like we’ve lost the plot. The tone is somewhere between black metal, medieval horror, and gallows comedy. The rules fit on a few pages. And somehow, despite or because of all of that, it produces some of the best table moments we’ve ever had. There’s a freedom in a system that doesn’t pretend the world is survivable. When everything is doomed anyway, players tend to let loose resulting in great sessions. If your character succumbs, it’s no bother; rolling up a new would-be-hero is pretty quick and fun.

The Mörk Borg third-party licence is also genuinely generous, which is part of why the ecosystem around it is so rich. Independent publishers can make and sell adventures without jumping through legal hoops, and the result is a sprawling, weird, wildly varied catalogue of content. Rattus Norwegicus sits proudly in that tradition.

The Adventure: Down the Stairwell

The setup is lean and effective: In the cursed city of Galgenbeck, the Rätfölk, the plague-bearing ratfolk, have made their base of operations beneath the streets. The players descend the stairwell. What happens next depends entirely on how clever, how lucky, and how quickly they can move before things go catastrophically wrong.

The dungeon spans nine rooms, each with its own flavour and its own ways to kill you. There’s an entrance reeking of dung and gambling rätfölk. A dinner hall with explosive moonshine. A kitchen staffed by a kidnapped chef who has developed severe Stockholm syndrome and absolutely does not want to be rescued. A temple where ratfolk are voluntarily feeding themselves to a Giant Devouring Slüg. A war room where the boss, who turns out to be a secret human in a rat costume, has plastered the walls with maps and unsolved riddles.

That last detail is worth dwelling on. The Boss is, in fact, a ratcatcher who has gone native. He will plead with the party if cornered, or swallow an acid pill and dissolve his own head rather than be captured. It’s the kind of deranged logic that makes Mörk Borg feel like itself, and Michael has deployed it with obvious relish.

The Slüg Problem

The adventure’s central tension mechanic is elegant in a horrible way. The Giant Devouring Slüg starts the session occupied, eating willing rätfölk in the temple, as one does. But open six doors, and the sacrificial supply runs out. The Slüg gets loose. From that point on, every corridor encounter roll has a chance of producing thirty hit points of acidic, devouring horror that will explode if it touches salt.

This is exactly the kind of ticking-clock design that makes OSR adventures sing. The party doesn’t know exactly when it’ll happen. They just know it will. Every door they open is a choice, and the dungeon keeps a quiet count.

Tables, Tables, Tables

Rattus Norwegicus is generous with its random tables, which is to say it’s generous with replayability. Before the session even starts, each player rolls on a rumours table — some true, some false, all useful for building suspicion and paranoia before a single die is rolled in anger. There’s a separate table for why your scvm has descended into this particular hellhole, ranging from mercenary contracts to a deep personal hatred of rats. And when you kill a rätfölk, you roll to loot the body — results ranging from nothing but greasy fur to a vial of Bubonic Plague (“better not open this one”).

The code-box in the boss’s lieutenant’s quarters deserves a special mention. Its contents are randomised across four options, each of which points toward a different published adventure — The Goblin Grinder, Bastard of the Badlands, The Black Stump, Devil’s Tomb. It’s a small touch, but it transforms what could be a self-contained one-shot into a hook for a longer campaign, which is exactly the kind of thing a good adventure should do.

The Illustrations

Nicolai Strøm, known on social media as @houseofadelsten, is Seidmann Games’ in-house illustrator, and his work is a significant part of what makes our catalogue look like itself rather than like everyone else. For Rattus Norwegicus, he’s produced original artwork that fits the adventure’s tone precisely: grotesque, dark and full of that good mood-setting.

Michael notes in his afterword that this is a remaster of an adventure he originally published on itch.io — and that Nicolai’s illustrations are a substantial part of what makes this version the definitive one. We’d agree. The art elevates the writing, and the writing gives the art somewhere horrible to live.

Who Is This For?

Rattus Norwegicus is for Mörk Borg players who want a tight, playable one-shot they can run on short notice. It’s for GMs who appreciate a dungeon with a sense of humour and a body count. It’s for OSR fans who want something that plays fast annd hits hard, and doesn’t outstay its welcome.

It won’t take you long to prep. The random tables do a lot of the work. The dungeon is small enough to run in a single session and weird enough to make that session memorable. It sits comfortably alongside our Shadowdark adventures — Dawn of the Goat [link: Dawn of the Goat on DriveThruRPG] and On the Ledge of My Seat [link: On the Ledge of My Seat on DriveThruRPG] — as the kind of thing we like to make: strange, lethal, and distinctly Norwegian in its general outlook on human survival.

How to Get It

Rattus Norwegicus is available on DriveThruRPG for $4.99 [link: Rattus Norwegicus on DriveThruRPG].

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