Everything goes downhill from there.
So, anyway, as noted in my post about bookporn, I accidentally received a copy of Isle of the Unknown with Carcosa, and quickly rectified this egregious error by legitimately purchasing the book.
To think there was a time when I thought Isle of the Unknown merely sounded neat.
(Also, before I proceed, there are a few spoilers, mostly in the form of, "Here's a neat thing you might see, with minimal details so that you only know you might see something matching this description.")
Isle of the Unknown is pure, unadulterated, old-school awesome. There's this island, and it's unknown, see?
Basically, Isle follows Geoffrey McKinney's hexcrawl format from Carcosa: this island is broken into hexes, each ten miles across (86 square miles overall). He has one entry on one interesting thing that can be found in each hex.
And that's it. That's the setup. That's the thing you order from Finland and await with baited breath.
Really, though, there's a lot of stuff crammed in these 125 pages.
Each interesting thing is, get this, actually interesting. It's Weird and Mysterious stuff in D&D, which frequently gets lost in all the "Well, the humans have towns and the elves have towns and I guess the goblins have towns and it rains sometimes" mundanity of it. You can read a little about that back-and-forth between James Raggi and Geoffrey McKinney here.
The product assumes no setting; this island can literally be dropped anywhere. Along with this idea, there is no backstory for the island — everything is inferred. There are people living here now (by default, they're chivalric-and-romantic-era France, but that's just a placeholder for whatever culture you want), and people lived here in the past, and a rumor suggests that maybe Carcosan Men lived here before that, but who knows?
What's left is all the weird stuff of the clash between the modern and ancient.
The interesting things fall under several broad categories. There are some monsters, some statues, some locations, some items, and some people.
The monsters are all weird. Some are terrifying, some are stupid-looking. The stupid-looking ones are frequently more scary than the overtly intimidating ones. Seriously, there's a thing that looks like a koala with octopus suckers, but it's one of the most awful things I've ever read. Meanwhile, there's this reptilian horror that is pretty manageable. 0-level guys could take him out with minimal difficulty.
You never can tell on this island.
The statues, locations, and items are similarly weird, and there's no telling how such a thing might go. Some statues grant boons, others grant banes, or animate and attack the adventurers. Most locations are towns, but some ruins dot the landscape. These tend to be the least weird, but again, you can't know — towns are frequently the gateway to the weird, as residents offer quests relating to the magic of the isle. Old relics are also strewn about the island, and again reward adventurers who are cautious.
By far, however, my favorite part features the people. This island boasts an order of clerics, and magic-users of all sorts have been drawn to the isle, ostensibly to study its properties (or just to find an isolated place to experiment). The clerics represent the human intrigue of the island, connected as they are with the towns and cities dotting the countryside. Some of the order's secrets are suggested by the actions of these men, and as with everything else, they may aid or hinder adventurers who encounter them.
And then there are the wizards.
Maybe the old civilization crafted a place rife with magic, or maybe it's just secluded, but there are a few magic-users on this island. Each one is unique, having found some personal demense and practiced magic there.
Basically, Geoffrey McKinney answered one of my chief complaints about D&D, being the magic system. Magic should be an Art, but it has aspects of a science in D&D, because everything is so rote. Isle of the Unknown suggests that this is not uniformly true, because his magicians are weird. Maybe most of the murderhobo magicians in the world are, say, self-made, ruthless men in the vein of Steve Jobs — they go out, do weird and amazing things, dick some people over, and get famous and wealthy beyond mortal comprehension — but the magi on the Isle are like those weird art-school students who live in a commune formed from draperies in a rickety old sawmill, and they turn their life into art.
These magi take magic and own it, wholly entangling themselves and the Art until there is no distinction. There's the one who has completely control over the crabs from the nearby lake, or the one who has secured immortality by sequestering his consciousness in a piece of vampiric artwork.
These guys are truly Masters of the Art.
One more thing: as with Carcosa, this book is damn pretty. Everything is in rich, lavish color, with detailed maps of the island, evocative images of the monsters, and full-page splashes of the strange and varied magic-users of the island. As noted in the above link regarding Mr. Raggi and Mr. McKinney's thoughts on the Isle, this is as much a hexcrawl as it is an art project.
In short, Isle of the Unknown is weird romp of a hexcrawl through a landscape relatively untouched by human hands. You might get rich by investigating the secrets of the Isle, but it is more likely that you will be changed by it, and you will find yourself away from the mundane and fully immersed in the Weird.