Review: The Book of Unremitting Horror – A Tasty, Gruesome Bestiary

This is a book that was originally published in 2008. I bought it in pdf format a long time ago, and recently, on a whim, I finally bought the hardcopy, which served as a pretext to read the whole thing again.

Now, this book has particularly graphic and disturbing content, so be forewarned: it is not for the faint of heart, and it pretty much requires every trigger warning I can think off.

If, like me, you have a profound love for monster books— one of the reasons I still buy old and new D&D books although I haven’t played D&D for a couple of years — then The Book of Unremitting Horror is an absolute treat. Originally published almost 20 years ago, it still feels remarkably fresh and unique. Unlike many RPG bestiaries that rely on familiar horror tropes, this book mostly explores original monster concepts, the likes of which you will not find elsewhere. Most of the entries are unsettling, some outright bizarre, while a few are derived more directly from folk horror.

While it has some minor flaws, its strengths more than make up for them, particularly if you’re looking for fresh inspiration. It’s also worth noting that its simple black-and-white layout marks it as something of another era, without textured backgrounds and elaborate graphic design, putting more focus on the text. The use of stark, visually shocking line drawings instead of colourful, painterly artwork allows the imagination to run freer. It invites you to make it your own rather than dictating a specific aesthetic.  

The Pros  

-A Vast and Unique Monster Compendium  

  One of the strongest aspects of the book is the sheer variety of monsters. While many horror bestiaries lean heavily on Lovecraftian or folk horror traditions, this one introduces creatures of a more surreal and/or gnostic flavour. That’s not to say you won’t find elements of folklore or gothic horror here—some creatures could fit neatly into a Vaesen campaign, while others would make fantastic additions to Call of Cthulhu. However, the real gems in this book are its most original creations, such as “The Practice,” which plays a crucial role in the Invasive Procedures scenario (which is sold separately, and which I absolutely recommend).  

- Evocative Artwork 

  Every creature is accompanied by detailed line drawings that capture the horrific essence of the beings described. Some of them are particularly gruesome and repulsive, others are just outright bizarre, but I don’t think there is a single design that is boring or uninspiring. 

- A Flexible but Fragmented Mythology  

  One of the more curious aspects of the book is its vague cosmology. The concepts of the Outer Dark and the Membrane (originating from the Esoterrorists RPG) provide a broad justification for the existence of these creatures, essentially allowing for anything the GM wants to introduce. This is both a strength and a weakness. On the plus side, it allows for incredible variety, with no strict canon to adhere to, meaning you can seamlessly slot in new horrors of your own making. However, the lack of a stronger thematic through-line means the monsters sometimes feel like a disconnected grab bag of horrors rather than parts of a larger, interconnected mythology. Beyond a general aesthetic—surreal, bleak, and violent— and a great focus on predators that consume humans in a way or another, there isn’t much of a cohesive framework tying them together, which could make it harder to build campaigns around them beyond the purely episodic.  

- Great Writing and Flavor Text 

  Many of the monster descriptions are prefaced by flavour text which are often so well-written that they read like complete mini- short horror stories in themselves. The writing is atmospheric and immersive, often sparking several scenario ideas just from a single entry.  

- Outstanding Scenario: Crook’s End

  The book includes ten scenario seeds and two complete scenarios. While the scenario seeds suggest ways to use the monsters specifically in the context of Esoterrorists campaign frame, many of them can be adapted to other contexts. They are all fairly interesting, but frankly there wasn’t a single one that made me jump from my chair, excited about immediately running a game. To be fair, this does not happen often to me, as I am very picky about what games I run.

As for the complete scenarios, they are not connected to the Esoterrorists setting, and can be run as horror one-shots. While both are interesting and very different from each other, one of them, Crook’s End, is a standout, delivering a brutal, terrifying haunted house experience. If you don’t mind the gore and ultra-violence (which can be veiled to a certain degree if necessary), this scenario is an instant horror classic. I’ve run it multiple times, and it never fails to chill the players.  

The Cons  

- Over-Reliance on Predatory Monsters  

  A significant portion of the monsters boil down to variations on “they eat people.” While this is a staple of horror, it does get repetitive when too many creatures operate with the same basic motivation. A few more creatures with unique or insidious goals would have balanced things out better.  Very few of the creatures have any agenda beyond their basic predatory instinct, which is in itself another limitation of this book. It is at times suggested that some of the creatures may have a more complex agenda, but few of the entries actually give any insight onto what that agenda may be (which is a shame, because when they do, my head immediately conjures a plot).

- Inconsistent Writing Quality  

  While much of the writing is great, a few entries feel weaker and uninspired. With such a large collection, it is unsurprising that not every creature is a hit, but it really feels like some entries are there just to increase the page count. 

- Organisational Issues 

  The book follows a general structure for each entry—flavour text, investigative clues, Gumshoe stats, and an explanation of the creature’s abilities and motivations. Unfortunately, not all entries adhere to this format, and it sometimes feels like too much information is missing. 

- Limited Guidance on How to use the Monsters 

  While some monsters clearly fit into investigative horror scenarios, others are more difficult to deploy effectively. A few entries provide direct advice on how to use them in a campaign, which is great, but many more are missing, and in some it would really help to have them. While the book sections on artifacts and scenario seeds do help in making sense of how to use more of the creatures, I think it would have made more sense to include a couple of scenario hooks with each entry, like in Vaesen.

Final Thoughts  

Despite occasional flaws, The Book of Unremitting Horror is an excellent addition to any horror GM’s collection - yes, even if you don’t play any Gumshoe game (like Esoterrorists, Trail of Cthulhu, or Fear Itself). 

If you enjoy reading monster books for inspiration, this one will undoubtedly spark ideas for other games such as Delta Green, or Call of Cthulhu, or even Vaesen. While the lack of a cohesive mythology makes it harder to establish a broader campaign narrative, it also means you have complete creative freedom to incorporate the book’s horrors in whatever way you see fit.