The setting of the game is an alternative 1950s Earth where humanity has come under attack from a wide variety of threats, ranging from destructive beasts to malevolent societies with ambitions of conquest, all originating from or otherwise tied to the depths of the ocean.
The line's success has led to several sourcebooks, including a spin-off game built around 1970s horror in the same way that They Came From Beneath The Sea! is built around 1950s science fiction; They Came From Beyond The Grave. This latter game has a sourcebook titled They Came From Camp Murder Lake!, which specifically focuses on the Slasher Movie genre and can be technically run as its own independent gameline.
This game provides examples of:
- AI Is A Crap Shoot: The Destroyer known as Brainbox; a World War II codebreaking machine eventually upgraded into a primitive computer which then grew into a full-fledged rudimentary AI. It was intended to be repurposed into an advertising analyzer to be used to generate greater profit for American corporations, but proved to be fixated on annihilating all non-American nations. Its creators deactivated it, disassembled it and mothballed it, but it was stolen by an aquatic alien force who rebuilt it. Then it upgraded itself into a self-sufficient mobile fortress-factory, destroyed or subjugated its liberators, and became obsessed with doing the same to humanity. Also, in a more comic example of this trope, it still can't stop randomly spewing out advertisements from American radio, involuntarily interjecting them into everything it says.
- Alternate History: In addition to the whole "invasion of monsters from the ocean" thing, Joseph McCarthy was eaten by a kaiju called King Clam, and as a result the Red Scare, whilst still an active influence in the world, is losing a lot of steam as humanity becomes more inclined to unite in the face of their fishy enemies.
- Atlantis: The city existed in the world of "They Came From Beneath The Sea", and the Human Subspecies that evolved after it sank are known as Atlantoids. However, they have lost the actual city and largely have begun integrating into humanity — except for a radical secessionist movement, who wish to reclaim their former home at any cost, and who believe that there are keys to finding it encoded in the brains of the most enlightened humans.
- Big Creepy-Crawlies:
- Aquatepillars are massive, multicolored seaslug-like creatures ranging from 10 feet long and 3 feet in diameter to 30 feet long and 12 feet in diameter. They are slow but relentless predators that attempt to slam into potential meals (aka, anything made of flesh) in order to paralyze them with the venomous hairs adorning their bodies before devouring their prey. They have voracious appetites and whilst capable of feeding on plantlife, they prefer flesh.
- The Primordials known as Bonellia Viridis Terribilis are literally spoonworms, a real-world aquatic invertebrate, grown large enough to feed on humans.
- If one is generous with the trope, the Gigantic Pillbugs, which are humanoid shaped and man-sized marine isopods.
- Even more generous with the trope is the Primordial called the Mariner's Menace — a gargantuan barnacle.
- Blob Monster: The Suspended are an unusual example, in that they are actually a non-slime organism of unknown form (beyond apparently being limbless) that use amphorphous masses of psionically-controlled slime as a kind of gooey Powered Armor.
- B-Movie: In addition to being the basic inspiration for the setting as a whole, B-Movies are a booming business in-universe... mostly because they're actually propaganda films intended to showcase that humanity — or at least the USA — is fighting and winning against "The Green Menace".
- Caps Lock: In They Came From Beyond the Grave, whenever Satan gets talked about he's always described as THE DEVIL HIMSELF. In keeping with the games horror comedy theme it doesn't take long to become perversely amusing.
- Devious Dolphins: The Sapient Cetaceans known as the Prefecture of the Pod are an alliance of evil dolphins and whales who seek to conquer humanity. They've also managed to conquer, or at least form an alliance with, some of the crab people.
- Elemental Embodiment: The Oblique is a strange creature of living water.
- Enclosed Extraterrestrials: The aptly-named Suspended, who use a sort of slime-based exosuit to operate outside of the water, as they can't breathe the oxygen.
- Enemy Civil War: One of the things that has kept humanity alive is that many of the different aquatic monsters and invaders are actively fighting against each other. In particular, Aquatepillars and the Primordials tend to eat anything else they encounter, to the point that the Iguanoids engineered the King Sea Serpents to destroy Aquatepillars, the Gigantic Pillbugs are in open war with the Glowing People, the Urchinfolk want nothing less than to utterly devour the Killer Kelp, the Crap People are apparently divided into warring factions over whether or not to ally with the Prefecture of the Pod, and the Anuradons want to conquer humanity in order to use them to wipe out their former Iguanoid masters.
- Five-Man Band: As a Storyteller game, the game doesn't exactly use a conventional class-based system. However, there are five distinctive "Archetypes" that serve as the equivalent of basic classes, even if players are informed they can custom-build their own character templates. Each Archetype has its own unique array of associated skills, "trademark" attributes, and "Tropes" (powers).
- The Everyman is any Badass Normal type character; they are the average joes, the regular guys and gals. Their personal Nemesis is the Primordial monster archetype, which represents the utter annihilation of the "normal" world in which the Everyman lives and thrives.
- The G-Man represents government and legal agents, giving them an authority that allows them to better control and manipulate standard civilians. Their personal Nemesis is the Spy monster archetype, which they view as the ultimate threat — and a dark reflection of themselves.
- The Mouth represents heroes with ties to the media; reporters, journalists, photographers and even actors. Their personal Nemesis is the Enslaver monster archetype, whose ability to manipulate human minds is too akin to what the Mouth does for comfort.
- The Scientist is, obviously, a Science Hero or Mad Scientist type, who uses their understanding of the way the world works to better fight the forces destroying it. Their personal Nemesis is the Invader monster archetype, which considers Scientists to be both major threats to eliminate and useful sources to probe.
- The Survivor is similar to the Everyman, but has more active experience with combat, or has at least been alienated from society as a whole. Often scarred by what they have seen, heard or done, Survivors are great monster-killers, but lousy at social interactions. Their personal Nemesis is the Destroyer monster archetype, whose bloodthirsty urges trigger a countering reaction.
- Frog Men:
- The Primordials known as anuradons are a species of humanoid frogs who evolved at around the same time as the iguanoids, but who are much more violent, aggressive and warlike. The iguanoids used Mind Control technology to pacify them, effectively turning them into a Slave Race, but the anuradons broke free of their control. Having survived the extinction event by retreating into the depths of the earth, they now seek to conquer humanity and use its numbers and technology to destroy the iguanoids.
- The Enslavers known as the Sirens of Ness are also described as resembling humanoid frogs or toads.
- Gone Horribly Right: The Killer Kelp were an attempt by Dr. Carmichael to create a force with which she could stop the Radion company's rampant pollution. Instead, she has unleashed a race of hyper-evolved plants that seek to conquer humanity and become the dominant life on earth.
- The Greys: The Glowing People look like Greys, but inhabit vast undersea cities. They abduct people to use them as slaves, and engineered the Gigantic Pillbugs as a Slave Race before the latter escaped.
- Horror Comedy: The game's basic genre, and Storytellers are advised to adjust the scale of silliness to scariness to suit the tastes of their play group.
- Humanity Is Infectious: Brain-eater eels technically only want to feed and reproduce... but they're also fully sapient creatures, and thusly they find humanity's culture and the wide range of stimuli it offers fascinating. It's not unknown for brain-eaters to spare their hosts for prolonged periods, so they can continue to enjoy the stimuli of human civilization.
- Human Sub Species: Atlantoids are a human subspecies that evolved to inhabit an underwater environment when Atlantis sank. They can be distinguished only by gills hidden behind their ears and under their pectoral muscles; it's believed, but unconfirmed, that they may only have blue or green eyes, and they have a higher than average incidence of heterochromia. They can freely interbreed with humans, and Atlantoid genes are recessive, to the point the vast majority of Atlantoids present in the world are "throwbacks" born to seemingly normal human families.
- Interspecies Romance:
- Gill-kin have been known to fixate on humans to the point of sometimes showing themselves to the object of their affections whilst dressed up nicely and holding a bouquet, clearly asking them on dates. As per the game's Horror Comedy tone, it's noted that some in the military fear that this is an insidious alien plot to subvert humanity through interbreeding.
- Jimmy Lewis, the so-called "Squid Rider", is a villainous ally of the aquatic menace at the behest of his lover; "The Squid that Sees All". She initially seduced him in the guise of a beautiful green-skinned humanoid woman, but even after revealing she was, in fact, a man-sized, bright green, bipedal female squid, his devotion to her never wavered. If anything, he thought her true form was more beautiful. A pity that in Jimmy's case, Love Makes You Evil.
- Kaiju: It's noted in the setting's lore that the Japanese invented this term specifically to refer to the larger monsters threatening the world, mostly the Primordials, and it's since been adopted by other nations.
- Les Collaborateurs:
- The Transatlantica Steamship Company, who have become aware of the Glowing People and who have formally allied with them in their goal to conquer the world, in return for being promised favored status as the overseers and governors once humanity became a Slave Race. To this end, they provide the Glowing People with human technology, human test subjects, and facilitate transport for the Glowing People's military.
- The Federation of Intelligent Sealife and Humans, a former top-secret military research unity dedicated to studying the various underwater horrors of this world to find a way to stop them, but who instead turned against their government masters and now seek to bring about a peaceful resolution to the conflict between species. By default, they're presented as unwitting dupes of one or more hostile Invader factions. Monsters of the Deep presents their extremist militant break-away faction, the Bureau for the Aquatic Kontrol of Earth.
- Lizard Folk: The iguanoids, an ancient race of reptilian humanoids who went into underwater cryostasis chambers to avoid the extinction event that killed the dinosaurs. They don't particularly hate humanity, but they are horrified by how humanity has abused the ecosphere, and combined with perceived similarities to their ancient enemies, the anuradons, they are convinced that humanity may need to be subjugated or even destroyed for the planet's own good.
- Love Makes You Evil: Jimmy Lewis, the Squid Rider, serves the mysterious whims of whatever aquatic horror he is unknowingly aligned with because he's so devoted to his she-squid lover that he will gladly steal, vandalize and murder for her.
- Mad Scientist: A minor terrestrial threat are mad scientists, with the most prominent example actually covered in detail being Dr. Carmichael, who created the Killer Kelp.
- Maybe Magic, Maybe Mundane: Nobody is sure if the were-lobster phenomena is something mystical or if it's perhaps rooted in some kind of bizarre underwater plague.
- Nuclear Mutant: The Uranium Man, a strange alien creature of living uranium that seeks out refined radioactive materials to consume, growing larger and stronger as he does so. He also broadcasts an aura of radiation, which can not only leave victims sick or dead of radiation poisoning, but also trigger mutations in flora and fauna.
- Our Sirens Are Different: The Sirens of Ness, a race of strange humanoid frogs with powerful mind-controlling abilities, which they use to capture scientists to exploit their technology and further their goals of conquest.
- Our Werebeasts Are Different:
- The monster called Teenage Shrimp; originally a troubled, aggressively antisocial teenager named Nyllon Tines, until he ate a radioactive shrimp and transformed into a wereshrimp, changing into a savage beast at high tide that would seek out those he perceived as his tormentors and deliver deadly stings. He was killed by the police, and then brought back to life by his Mad Scientist girlfriend Rosty Newlar, who then transformed him into a 50ft giant to battle Centopus. But something has gone wrong, and Nyllon has lost control of his bestial side; now he is a man by day, a murderous shrimp-thing by night, and at random times he becomes a 50ft tall shrimp-thing.
- The Seahorse People are giant, sapient seahorses called "omega hippocampi" who can induce a slownote shift between their natural form and that of a human or back again as they see fit.
- Path of Inspiration: The Church of the Wave Ascendant, a sleeper cult dedicated to an Invader species of the Storyteller's choice.
- Properly Paranoid: Between Enslaver, Invader and Spy type monsters, this is a world in which it is genuinely beneficial to be cautious about the people around you.
- Red Scare: The HUAC is still alive and well, although it's losing a lot of respectability in a world in which various aquatic horrors want to wipe out humans as a whole.
- Sapient Cetaceans: The Prefecture of the Pod are an alliance of evil dolphins and whales with super-technology. Rorqualasaur is an ancient, possibly alien, whale the size of a large island.
- Sea Serpents: The King Se Serpents; genetically engineered giant sea snakes created by the iguanoids as a predator to control the Aquatepillars.
- Shark Man: The Shark Clans, where the precise melding of human to shark varies wildly between individuals. All are generally violent, near-bestial brutes.
- Shout-Out:
- Each chapter begins with a verbal quote from a 1950s B-Movie. Chapter 1 opens with a quote from Attack of the Crab Monsters. Chapter 2 begins with a quote from It Came from Beneath the Sea. Chapter 3 with one from The Beast From 20000 Fathoms. Chapter 4 with one from the 1954 film adaptation of Literature/20000LeaguesUnderTheSea. Chapter 5 with The Thing from Another World. Chapter 6 opens with a quote from Creature From The Haunted Sea, and also features subchapters that open with quotes from Attack of the Crab Monsters and The Wild Women of Wongo. Chapter 7 opens with a quote from Them!. Chapter 8 features a quote from Plan 9 from Outer Space. Finally, Chapter 9 opens with a quote from The Blob (1958).
- The Aquatepillars combine elements of the monsters from The Monster That Challenged the World and The Creeping Terror.
- The Iguanoids are very reminiscent of the Sea Devils, an obscure amphibious offshoot of the more famous Silurians from Doctor Who.
- The Gill-kin are obviously based on the Creature from the Black Lagoon.
- Teenage Shrimp is an aquatic parody of I Was a Teenage Werewolf and I Was A Teenage Frankenstein.
- Teenage Shrimp's writeup explicitly refers to The Amazing Colossal Man and Attack Of The Fifty Foot Woman.
- Sourcebook: The gameline is home to a number of sourcebooks, including spin-off gameline They Came From Beyond The Grave:
- Heroic Land Dwellers; 16 sample playable characters, each with their own backstory and character sheet.
- Monsters of the Deep; expanded bestiary, offering various new threats for the storyteller to feature in their campaign.
- Tales of Aquatic Terror; four complete scenarios for storytellers to run.
- They Came From the Snake-Filled Submarine!; an adventure in which a submarine is invaded by reptilian aquatic horrors.
- Party Beach Creature Feature!; an adventure for Beneath the Sea about a beach town being invaded by hostile gill-kin.
- They Came From the Bikini Beach Party!; new player-centric material for characters based on beach-movies, especially as they overlap with old sci-fi and horror films. Offers two new archetypes; "The Beach Hero" (archenemy: Enslavers) and "The Heartthrob" (archenemy: Terrestrials).
- They Came From Outer Space!; A short pamphlet on rejiggering the game for use with extraterrestrial threats rather than subaquatic ultraterrestrials. Also features the new Archetypes "The Astronut" (archenemy: Invaders) and "The Eccentric" (archenemy: Enslavers).
- Stealthy Cephalopod: Thaumocs are a race of hyper-advanced mimic octopuses who infiltrate human society by using headless Artificial Human bodies and disguising themselves as the human's head.
- Straight Edge Evil: One of the most reliable ways to identify if a victim has become the host of a brain-eater eel is if they give up drugs of any kind, including alcohol and nicotine. This is because the parasite has an extremely negative reaction to such toxic chemicals, so forcing the host to indulge in them will compel the eel to flee the body.
- Stylistic Suck: Not the games themselves, but the movies they emulate are meant to be
incredibly cliché and shot on shoestring budgets, which is reflected in several Cinematics. - Tentacled Terror: Centopus and the Gargantuan Squid. Technically also the Thaumocs, although they're a lot smaller than normal examples of this trope.
- Threatening Shark: You have Robot Sharks, which are members of the Robot Race rebuilt into shark bodies in a process that invariably drives them insane; the Shark Clans, a widespread array of Shark Man Barbarian Tribes; and the Walking Dogfish, which are large amphibious sharks with legs and dog-like mentalities used as pets by the gill-kin.
- Token Heroic Orc: Several of the aquatic aliens are not actually hostile towards humans.
- Gigantic Pillbugs really couldn't care less about humans; their enmity is reserve solely for the Glowing People. Unfortunately, they have a cultural hostility to faked materials and their larval stage are voracious, non-sapient predators.
- The vast majority of Atlantoids are harmless, since it's only in recent times that their population began to grow to noticeable levels. The problem are the bad eggs who make up the secessionist movement, who have fixated on the idea of returning to the lost city of Atlantis.
- The gill-kin are, much like the Atlantoids, a largely peaceful race that is perfectly content to live and let live. Indeed, they show a great deal of curiosity about humans and their creations. The only exceptions are the ferals, which are gill-kin whose egg-clutches were poisoned by pesticides, leading to mental instabilities in the surviving hatchlings.
- Trademark Favorite Food: Another major identifier of brain-eel infestation is a fixation on eating fatty food; the larval eels that will be laid in the host's corpse when the adult moves on will feed on the body's fat content to fuel their growth into adulthood.
- Ultraterrestrials: Pretty much every aquatic humanoid race in this game is an ancient species that evolved prior to or alongside humanity. The closest thing to "proper" aliens in the setting are the Robot Race from 3000 A.D, which are humanity's time-traveling transhuman descendants, and possibly the Glowing People, whose underwater lairs are contained in oxygen-filled domes and whose origins are otherwise a mystery.
- Weird Historical War: It's the Cold War... but humanity is under attack by aquatic ultraterrestrials.
- Well-Intentioned Extremist: The Robot Race from 3000 A.D. are time-traveling Invaders whose goal is to prevent humanity from undergoing the near-total nuclear apocalypse which forced the humans of their timeline to upgrade into robot-people in the first place.
