Delta Green

We travel light, we probe deep, and we strike hard. We're Delta Green, and we may be outlaws and cowboys and fools, but we've kept this green ball of shit safe and sound for longer than most people have been alive.

—Reginald Fairfield

Choose federal law enforcement. Choose the military. Choose NASA or the CDC. Choose lying to your superiors. Choose to ruin your career. Choose no friends. Choose divorce. Choose life through the bottom of a bottle. Choose destroying evidence and executing innocent people because they know too fucking much. Choose black fatigues and matching gas masks. Choose an MP5 stolen from the CIA loaded with glasers, with a wide range of fucking attachments. Choose blazing away at mind numbing, sanity crushing things from beyond the stars, wondering whether you'd be better off stuffing the barrel in your own mouth. Choose The King In Yellow and waking up wondering who you are. Choose a 9mm retirement plan. Choose going out with a bang at the end of it all, PGP encrypting your last message down a securely laid cable as an NRO Delta wetworks squad busts through your door. Choose one last Night at the Opera. Choose Delta Green.

—Anonymous

An acclaimed 1997 sourcebook for the famous Call of Cthulhu tabletop roleplaying game, Delta Green tells the story of the eponymous organization, a secret United States agency born of the Federal raid on Innsmouth in 1929 and tasked to protect the country from paranormal threats. After an operation gone horribly wrong in Cambodia in the '60s, Delta Green was officially shut down - but its leaders, aware of the things lurking in the cracks of reality, continued the fight illegally, stealing resources from the government, carefully picking new members from the federal agents community, and generally acting like rightfully pissed off Cowboy Cops in their battle against the supernatural. It would not be until the 1994 assassination of Major General Reginald Fairfield, Delta Green's de facto leader, than DG would take up their current incarnation: a deeply hidden conspiracy in the labyrinthine world of the United States federal agencies, structured in semi-independent cells.

Delta Green is heavily based on classical conspiracy/UFO theories, meshing them with the Cthulhu Mythos milieu: DG themselves are a spin on The Men in Black, but there are also other shadow agencies involved, including the now famous Majestic 12 group that deals with the Greys (actually Mi-Go in disguise). Other players are the Karotechia, occultist Nazis serving an "ascended" Hitler; the Fate, a criminal organization that makes heavy use of Mythos creatures and spells for fun and profit; SaucerWatch, a naïve yet well-funded UFO research group that may be closer to the truth than they know; and the Cult of Transcendence, among others.

The tone of the book is even bleaker than standard CoC: where the basic game has investigators struggling against Mythos creatures and the cultists that serve them (and DG does include its fair share of battle against these forces) the primary adversaries are evil and/or utterly amoral humans that (attempt to) use the forces of the Mythos for their own benefit, and are becoming as amoral as them. The Stars are Coming Right, and there may not be anything that Delta Green, or anyone else can do about it...

But it doesn't mean they have to make things easy for them.

Tropes used in Delta Green include:

Aliens and Monsters: And not all of them are betentacled.
Ancient Conspiracy: Both averted and played straight with the Cult of Transcendence. As the Alta Vendita, they've been around since the Crusades, but they underwent a significant change in leadership and purpose after the First World War showed them how much their attempts at running the world had failed.
Brain Food: Agent NANCY is DG's foremost forensic analyst and autopsy expert. She is, in fact, a ghoul, and can obtain knowledge from dead bodies by devouring their brains.
Badass Normal: Many NPCs, such as the late Major Fairfield, Captain Forrest James or MJ-12's Adolph Lepus. The PCs can also become this.
Broad Strokes: According to the offical site, nothing in Delta Green is canon. instead, they encourage players to use whatever works for their game.
Code Name: Every DG agent has one. Also, there are the MJ-12 projects, and the various classified documents used throughout the game.
Conspiracy Theories: One half of the book's inspiration.
Cosmic Horror Story: Even without all the human cultists, sorcerers and others dealing with Mythos forces, humanity would be pretty much done for. With them around, It Gets Worse.
Cthulhu Mythos: This is the other half.
Dark Is Not Evil: Ghouls have a bit of that vibe going on, depending on the particular group or individual. Of course, players shouldn't rely on it too much unless they want to become lunch.
Did You Just Flip Off Cthulhu?: It can be argued that this is the best DG can hope to do.
Downer Ending: Surprisingly averted: according to the setting's official works, although Earth is eventually wiped out and all life on it eradicated, a substantial amount of humans manage to escape to Mars, various outer-orbit moons, outside the solar system altogether, and into the Dreamlands. There are even supplements and rules for playing a game post-destruction of Earth.
Ghostapo: The Karotechia—at least, what remains of it. An eldery worshipper of Yog-Sothoth, an undead Mad Scientist Necromancer mixing the legacies of both Herbert West and Dr Munoz from Cool Air, a humanitarian ubermensch who gets immortality and invincibility in the bargain, and the "ascended" spirit of Adolf Hitler (at least, they think it's Hitler...).
The Government: Many real-life US Federal agencies are provided for PCs to be part of, from familiar ones like the FBI and the DEA to the more obscure like FinCEN or the National Security Council. Countdown extends the roster to a number of foreign agencies.
Government Agency of Fiction: From DG and MJ-12 to equivalents in other countries, like the British PISCES.
Government Conspiracy: Majestic 12. Delta Green itself used to be this.
- Alternatively, if you believe one Delta Green Agent: "We're the government conspiracy. Those guys are just the government".
- PISCES can be considered a variation as well considering that it's been taken over wholesale by the Shan.
The Greys: The high-tech aliens cutting secret deals with MJ-12 for fun and profit. Of course, they are not what they seem.
Gut Feeling: The reason the Mi-Go are so interested in humans is our (to them) unnerving capability to elaborate accurate answers with little information and no clear logic chains of thought.
Interservice Rivalry: All the time between the various real-world agencies. Delta Green and MJ-12 used to have this in the short period where both officially worked for the US government.
Just Before the End: In some level, everyone knows that there is not much time left for humanity. This is why the Mi-Go created the Grey deception: to extract as much information as possible from humans before our time runs out.
Knight Templar: Delta Green agents used to go too far in their quest to both protect the American populace from the supernatural and keep the existence of the latter (and itself) a secret, particularly in the Fairfield era. Some still do.
The Masquerade: Delta Green fights to keep the existence of the paranormal a secret from the public at large. Sometimes, that involves neutralizing innocents.
Mind Screw: The Hastur Mythos.
The Nineties
Psychic Powers: There are a few optionnal rules for those; PISCES is the most knowledgeable about the subject.
Psycho for Hire: Adolph Lepus.
Puppeteer Parasite: The Shan, of course.
Pyrrhic Victory: This is the absolute, insanely-optimistic, ridiculously-unlikely best outcome of humanity's struggle. The more likely outcomes are much worse.
- And even then we managed to do it. Earth is gone but Humanity has spread amongst the stars.
La Résistance: The Army of The Third Eye, against the Shan.
Sacrificial Lamb: "Friendlies" are those people that support DG's cause but are not fully inducted into the conspiracy. Delta Green maintains a database with full information on each and every one, so that they can be properly "taken care of" if the need arises.
Shown Their Work: The bibliography shows a respectable collection of material regarding world history, UFO folklore, and the praxis of the US intelligence community.
The Sociopath: Adolph Lepus, litterally, as he has an antisocial personality disorder.
Taking You with Me: Reginald Fairfield's last stand.
The Vietnam War: An unsanctionned operation in that time and its disastrous aftermath is what made the US government dissolve Delta Green.
Those Wacky Nazis: The Karotechia.
Well-Intentioned Extremist: The Army of the Third Eye are mostly crazed fanatics, but what they fight against is much worse. Delta Green itself can come off as this at times.
X Meets Y: Call of Cthulhu meets The X-Files.
- Despite this, however, Delta Green actually predates the show by more than a year.