Carcosa is my favourite RPG book that I actually don't like at all. I am obsessed with it, but really I am obsessed with the idea of it. I love the premise, the overall aesthetic of the thing. I love the uneasy mixture of genuine horror and pulp nonsense, of grotesque violence and gonzo comedy. I love that it's basically a Kingdom Hearts/Super Robot Wars-style crossover of every Lovecraft-adjacent author ever. I love the sense of intense potentiality in the setting, the feeling that over the course of a few sessions your players could very easily seize godlike power, or trigger an eldritch apocalypse, or just die of sepsis in a ditch.
What I don't love is anything that's actually in the book.
Once you start reading the details, all you find is one limitation after the other. McKinney created a wonderful playground for the imagination, but it seems like he didn't actually want to play there. Consider this quote from the section on "Artifacts of the Great Race":
Humans, however, find it almost impossible to use these outré objects. Only humans with an intelligence of at least 17 can even possibly do so. After each month of continuous study, such a human has a 5% (non-cumulative) chance of understanding the item well enough to make some use of it.In other words - here's a bunch of cool stuff, but it's statistically improbable that any of your characters will ever be able to use it.
Or the section on sorcerous rituals, most of which require expensive treasures, human sacrifices, or quests to extremely dangerous locations. Even if all the requirements are met, the cosmic entity still gets a saving throw, and:
The Referee must make the being’s saving throw in secret. If a ritual does not work, the Sorcerer does not know why:How is this conducive to any kind of entertainment at the gaming table? If the PCs are trying to complete a ritual, it's just an exercise in frustration. If the PCs are trying to prevent an evil sorceror's ritual, it opens the door to a sad anticlimax: "You failed to stop him in time... but luckily Cthulhu made its saving throw so nothing happens."
The ritual might be defective and thus will never work.
The Sorcerer might have performed the ritual incorrectly.
The entity might have made its saving throw.
Once you get past the long and pointless list of rituals (most of which don't do anything useful even if you go to the trouble of completing them) you reach what should be the real meat of the book: the hex descriptions. But here, too, McKinney seems to have little interest in the possibilities of his own material. So many hex entries are literally just a monster name and a number, as if rolled right off a wandering monster table. But the really baffling ones are things like this: "Tens of thousands of ancient stone burial vaults dot these barren plains. Every one of them has been broken open and emptied." Or: "A shadowy figure lurks at the edge of the forest, watching intently. Though it may be a Black Man or a Purple Man, it is impossible to tell for sure, and he disappears deeper into the trees if pursued. No amount of searching or pursuit will result in finding him."
In other words: "Something here appears to be interesting, but on further investigation, it isn't. At all."
I know some people praise this kind of brief hex description because "it can serve as a starting point for the DM's imagination". But most of Carcosa's hexes are so brief that they give you nothing at all to work with, or worse, actively stifle imagination by negating possibilities.
The monster descriptions are similarly low-effort. Most of them boil down to generic blobs or crazed mutants that attack on sight. Many Lovecraft deities are listed, and although there's a certain goofy charm in learning that Azathoth, "the monstrous nuclear chaos beyond angled space", has 19 armour class and 60 hit dice, ultimately the descriptions of them are so brief as to make each one indistinguishable. McKinney's attitude seems to be: "You've read the original stories, so I don't need to put in any effort here."
Yet even that is too kind because McKinney has managed to make a lot of the Lovecraft monsters less interesting than in their source material. For example, Carcosa claims that creatures as diverse as shoggoths, mi-go and Deep Ones are all numbered among the "six main spawn of Shub-Niggurath". This attempt to systematise the unruly hodgepodge of the Lovecraft cosmos is reminiscent of the misguided efforts of August Derleth, who notoriously tried to fit Lovecraft's pantheon into neat boxes based on the classical elements of Earth, Air, Fire and Water. But cosmic horror really only works when the uncanny defies logical classification. The fact that Lovecraft's meta-universe is crowded with beasties and barely held together is part of its allure.
A review of Carcosa, especially a critical one, can't be complete without talking about the rape content. Because it created such controversy at the time of release, I'm always surprised to find how little there actually is in the book: I think it's just two or three rituals and one monster description. I absolutely think it should not be included in the book. Any reasonable DM won't use it anyway, and it makes it much harder to talk about the setting when you have to preface any discussion with "but I'm not into the rape stuff".
That said, I don't believe that the depictions of cruelty and torture in the ritual section are entirely gratuitous. It does add something new to the Cthulhu mythos. The traditional theme of cosmic horror has been "the universe is full of powerful beings that don't care if something horrible happens to you". Carcosa's rituals twist this a little: here, the powerful beings do care about horrible things happening to you, but they care for alien reasons beyond comprehension. But I really question whether this theme can be ably explored in a roleplaying game, much less in a game of gonzo hack-and-slash D&D.
Conclusion... look, I would be an asshole if I didn't give credit where it's due to a book that I've written a bunch of blog posts about. McKinney has definitely created a world that is fundamentally compelling on some level. But if you're reading this review to decide whether to buy it, I'd say... maybe don't bother?
Even aside from the fact that it's published by a guy who stands up for (alleged) rapists - the book doesn't give you anything you can't get yourself. Instead, I recommend you read the source material (Chambers, Smith, Lovecraft, Lindsay, and uh... Burroughs but maybe just watch the movie instead). Look at the artwork associated with Carcosa and read what other D&D bloggers have written about it. Then just imagine what's inside the book itself, and you will probably come up with something better than the disappointing reality.