[[quoteright:350:http://static.tvtropes.org/pmwiki/pub/images/dgsplash.gif]]
[[caption-width-right:350:Welcome to your new job, rookie.]]

->''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'''

->''[[Literature/{{Trainspotting}} 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 sourcebook for the famous TabletopGame/CallOfCthulhu tabletop roleplaying game, Delta Green tells the story of the eponymous organization, a secret United States agency born of the Federal raid on [[TownWithADarkSecret Innsmouth, Massachusetts]] 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 Cop}}s 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 CthulhuMythos milieu: DG themselves are a spin on TheMenInBlack, 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, [[{{Ghostapo}} 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 na´ve yet well-funded UFO research group that may be closer to the truth than they know; and the [[AncientConspiracy Cult of Transcendence]], among others.

The tone of the book is even [[CrapsackWorld 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...

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

For the ''other'', ''slightly'' less depressing, ''slightly'' funnier Lovecraft-meets-spy-fiction setting, see ''TheLaundrySeries''.

!!This game provides examples of:

* AliensAndMonsters: And not all of them are [[CombatTentacles betentacled.]]
* AncientConspiracy: 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.
* ArgentinaIsNaziland: The [[{{Ghostapo}} Karotechia]], Hitler's occult division whose remnants are hiding in the Amazon.
* AscendToAHigherPlaneOfExistence: ''Through A Glass Darkly'' features a machine that can allow a person to do this.
* BrainFood: Agent NANCY is DG's foremost forensic analyst and autopsy expert. [[spoiler: She is, in fact, a [[ImAHumanitarian ghoul]], and can obtain knowledge from dead bodies by devouring their brains.]]
* BadassNormal: Many [=NPCs=], such as the late Major Fairfield, Captain Forrest James or MJ-12's Adolph Lepus. The [=PCs=] can also become this.
* BroadStrokes: According to the offical site, nothing in Delta Green is canon. instead, they encourage players to use whatever works for their game.
* ChurchOfHappyology: The Enolsis Foundation. In this setting, of course it has a [[DarkSecret horrible secret]].
* CodeName: Every DG agent has one. Also, there are the MJ-12 projects, and the various classified documents used throughout the game.
* ConspiracyTheories: One half of the book's inspiration.
* CosmicHorrorStory: Even without all the human cultists, sorcerers and others dealing with Mythos forces, humanity would be in pretty deep trouble. ''With'' them around, though, they're utterly screwed.
* CrapsackWorld
* CthulhuMythos: This is the other half.
* DarkIsNotEvil: 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.
* DarkerAndEdgier: DG is like a grimdark X-Files.
* DidYouJustFlipOffCthulhu: It can be argued that this is the best DG can hope to do.
* DownerEnding: Delta Green fights the fires it sees, but it's all going downhill. Some modern [=CoC=] material hints at possible evacuation to space habitats or the Dreamlands, but nothing positive or canonical.
** [[spoiler: The Delta Green short story "After Math" details the end of the world through the eyes of an elderly Delta Green agent.]]
* {{Ghostapo}}: The Karotechia -- at least, what remains of it. An eldery worshipper of Yog-Sothoth, an undead MadScientist {{Necromancer}} mixing the legacies of both [[ReAnimator Herbert West]] and Dr Munoz from ''Cool Air'', a [[ImAHumanitarian humanitarian]] ubermensch who gets immortality and invincibility in the bargain, and the "ascended" spirit of Adolf Hitler (at least, they ''think'' it's Hitler...).
* GoMadFromTheRevelation: Let's just say that the suicide rate in Delta Green is above average.
* TheGovernment: 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.
* GovernmentAgencyOfFiction: From DG and MJ-12 to equivalents in other countries, like the British PISCES.
* GovernmentConspiracy: 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 [[spoiler:considering that it's been taken over wholesale by the Shan.]]
* TheGreys: The high-tech aliens cutting secret deals with MJ-12 for fun and profit. Of course, [[spoiler:they are not what they seem.]]
* GroinAttack: The Skoptsi sect in Russia does this to themselves -- all members of the cult must undergo castration.
* GutFeeling: 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.
* InterserviceRivalry: 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.
* JustBeforeTheEnd: In some level, everyone knows that there is not much time left for humanity.[[spoiler: This is why the Mi-Go created the Grey deception: to extract as much information as possible from humans before our time runs out.]]
* KnightTemplar: 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.
** In the words of one DG agent, "we do the horrific to prevent the apocalyptic". Later in that story, the same agent deliberately, and (we are led to believe) needfully, shoots a baby.
* TheMafia: The Fate is New York City's magic-using organized crime cartel.
* TheMasquerade: Delta Green fights to keep the existence of the paranormal a secret from the public at large. Sometimes, that involves [[HeKnowsTooMuch ''neutralizing'' innocents.]]
* MindScrew: The Hastur Mythos. Also SurrealHorror.
* TheNineties
* NoSuchAgency: DG started off as an official one. Now it's an unauthorized non-existent agency.
* PsychicPowers: There are a few optional rules for those; PISCES is the most knowledgeable about the subject.
* PsychoForHire: Adolph Lepus.
* PuppeteerParasite: The Shan, of course.
* PyrrhicVictory: This is the absolute, insanely-optimistic, ridiculously-unlikely ''best'' outcome of humanity's struggle. The more likely outcomes [[ApocalypseHow are]] [[EarthShatteringKaboom much]] [[TheEndOfTheWorldAsWeKnowIt worse]].
* RenegadeSplinterFaction: Following their disbandment, Delta Green for the U.S. government. However, their ruthless actions are partly justified.
* LaResistance: The Army of The Third Eye, against the Shan.
* RockMeAsmodeus: Charnel Dreams is one of the most popular bands in New York City. Their lead singer is the head assassin for the Fate, worships Nyarlathotep, and works Cthulhu Mythos spells into the lyrics of his songs.
* SacrificialLamb: "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.
* ShownTheirWork: The bibliography shows a respectable collection of material regarding world history, UFO folklore, and the praxis of the US intelligence community.
* TheSociopath: Adolph Lepus, literally, as he has an antisocial personality disorder.
* TakingYouWithMe: Reginald Fairfield's last stand.
* UnderNewManagement: [[spoiler: The novel ''Through A Glass Darkly'' has much of MAJESTIC-12's leadership killed off or otherwise disposed off, causing Forrest James to assume command.]]
* UsefulNotes/TheVietnamWar: An unsanctioned operation in that time and its disastrous aftermath is what made the US government dissolve Delta Green.
* ThoseWackyNazis: The Karotechia.
* WellIntentionedExtremist: 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.
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