Trail of Cthulhu is another horror fiction role-playing game based on the stories written by H. P. Lovecraft and The Cthulhu Mythos they inspired, much like its established 'rival' The Call of Cthulhu RPG. The game, written by Kenneth Hite, is published by Pelgrane Press, is one of several that use the GUMSHOE rules set.
The default setting for the game is the 1930s, and the background material makes it clear what a grim and ominous decade that was. There's a great essay on how to treat the rise of totalitarianism in the game.
There's also a lovely section on "Campaign Frames," which give the group of investigators an overarching reason to tackle mysteries together. One of the supplied frames is centered on the scholars at Miskatonic University, another is a 1930s version of Delta Green's quasi-governmental evil-fighters, and a third describes the "Bookhounds of London."
The rules provide for two "idioms" or modes. Pulp mode is close to the feel of CoC, which has always been more like the sword-in-fist Mythos stories of Robert E. Howard than Lovecraft's writings. The characters are tough and can shake off some supernatural insights with a shrug and a swig of whisky. The Mythos horrors can be thwarted, and packing heat (especially shotguns) is a good idea. And why stop at one gun? Use one in each hand, so you can fire twice as fast.
While building on the older game, ToC also cuts through the dense flora of CoC material that's built up over the decades, and goes back to Lovecraft to get the inspiration for the Purist idiom. In this mode, the characters are fragile mentally and physically. A "good" ending to a scenario might be that a character or two survive to tell the tale, much like in Lovecraft's stories.
The Mythos section is the single largest section in the book at over 80 pages long. Here are included rules for Mythos, natural and supernatural creatures, spells and spell casting (not good for stability or sanity!) and cults and cultists. The descriptions of the creatures are quite atmospheric and give some nice examples of the kind of clues such creatures would leave behind, and what abilities would find them. For example, the following is the Forensics evidence that might be left behind by a Dark Young of Shub-Niggurath. “The knife wounds didn’t kill him - they were superficial cuts at best - although the blood loss was serious even before whatever happened. The face and mouth cavities are full of blackish pus. Ulcerated open sores are on the anterior of the body, though that clear grease has dried now. The expression on what’s left of the face is… well, if you didn’t know better, you’d say it was religious ecstasy.”
Hite's writing skill is very impressive, as is his grasp of the Mythos and his determination to make a better game of them. In particular, the section on the Great Old Ones and Outer Gods is genius. Instead of learning that Hastur has 150 HP and 30 points of armor, we're told that:
"Hastur is a sentient (or at least self-willed) meme, or rather a viral complex of memes centered on alienation, ennui and despair. If, say, an artist depicts futile conversations on the edge of reality, she inculcates Hastur into the belief systems of her susceptible viewers. "Seeing The Yellow Sign" is a kind of perceptual stigmata that occurs as the brain begins to become convinced of Hastur's centrality."
But that's just one of 11 interpretations of the nature of Hastur that Hite gives us. It's up the GM to decide which one, or which ones, apply.
The alternatives are as follows:
• Hastur the Unspeakable dwells near the star Aldebaran in the constellation Taurus, possibly trapped in the gravity well of a dark neutron star. He is an octopoid Great Old One similar in form to Cthulhu, with an unbearably horrific face. He has an active cult on Earth, especially among the Tcho-Tcho people and experimental artists.
• Hastur is the embodiment of entropy and decay. Just as intelligence is merely a local manifestation of higher order, Hastur is the mirror image of that, a kind of localized antiintelligence that manifests as paranoia, despair, futility, unreason, and ennui. Whether Hastur has any “real” existence is impossible to say definitively.
• Hastur is not the god’s true name, but that of one of his cult centers. He is better called the Magnum Innominandum (“the Great Unnameable”) or He Who Is Not To Be Named. According to occult legend, speaking the name of the god three times summons him, with gruesome consequences.
• Hastur, The King In Yellow, is connected with The Yellow Sign, the dream-city of Carcosa (variously located in the Hyades star cluster and in primordial Mongolia), and the mystical Lake of Hali, as well as the things that dwell therein.
• Hastur is the leader of the Great Old Ones associated with the Element of Air, and therefore with flight through outer space. His servitors, the byakhee, fly both astrally and physically between Aldebaran and Earth, and to other locations where Hastur has made his presence known.
• Hastur, the Feaster From Afar, is a black, shriveled, mantashaped flying entity with extensible taloned feelers. Its eyes and aura glow iridescently with no known color, and it liquefies and consumes its victim-worshippers’ brains, draining them through its feelers and merging their consciousness with itself.
• Hastur’s powers are greatest on high plateaus (such as Leng or Tsang) and mountaintops. His cult anciently included shepherds who feared his wrath but learned to placate him and slowly came to worship him.
• Hastur appears as a boneless, scaly, slug-like creature bloated with fluid. Those who promise themselves to Hastur become as such creatures over time as they gain in eldritch power and knowledge.
• Hastur is an Outer God, the incarnation of (or a sentient facet of) the weak nuclear force of radioactive decay, one of the four fundamental forces within our space-time. As such, Hastur is invisible and can only be sensed psychically as a kind of crumbling pressure.
• The Not-To-Be-Named is the consort-god of Shub-Niggurath. These two deities, representing decay and fecundity, entropy and gigantism, melancholy and mania, are the historical substrate of all human religion, the Dying God and the Earth Mother. Their true worship still occurs in K'n-yan.
Inspired by the story of the same name, an adventure has been published for the game firmly based upon the mythos.