Delta Green is a setting for the Call of Cthulhu role-playing game. Delta Green was created by Adam Scott Glancy, Dennis Detwiller, and John Tynes of Seattle gaming house Pagan Publishing. Set in the modern day, characters are members of a renegade secret United States government organization – itself named Delta Green – dedicated to combating the horrors of the Cthulhu Mythos. The concept was introduced in the seventh issue of "The Unspeakable Oath", a Call of Cthulhu fanzine created by Pagan Publishing, in early 1993. Four years later, the Delta Green supplement appeared and spawned a number of its own supplements and novels.
The premise is similar to the X-Files, drawing on the federal alphabet soup folklore, UFO conspiracy theory, the Nazi Ahnenerbe organization, and other modern legends in addition to the Cthulhu Mythos.
From a game perspective, the purpose of Delta Green is to provide character groups with motivation, resources, a reason for working together, and a source of replacements for characters who go mad or die.
In 1998, Delta Green won the Origins Award for Best Roleplaying Supplement of 1997. The setting also won two awards in 2000, Best Game-Related Novel of 1999 for Delta Green: The Rules of Engagement and Best Roleplaying Supplement of 1999 for Delta Green: Countdown.
As of beginning of 2005, following Delta Green books were published by Pagan Publishing:
- Delta Green (sourcebook) – the basic sourcebook;
- Delta Green (sourcebook d20 edition) – 2007, the basic sourcebook (updated for the d20 system) ISBN 1-887797-23-8;
- Delta Green: Countdown – 1999, by John Tynes, Dennis Detwiller and Adam Scott Glancy, ISBN 1-887797-12-2 – the 2000s sourcebook;
- Delta Green: Alien Intelligence – March 1998, ISBN 1-887797-09-2 – short stories collection;
- Delta Green: Dark Theatres – 2001, short stories collection ISBN 1-887797-17-3;
- Delta Green: Rules of Engagement – 2000, by John Tynes – a novel ISBN 1-887797-16-5;
- Delta Green: Denied to the Enemy – 2004, by Dennis Detwiller – a novel, set during World War II &ndash. ISBN 1-887797-24-6;
- Delta Green Eyes Only Vol. 1: Machinations of the Mi-go – ISBN 1-887797-13-0 – limited edition game supplement;
- Delta Green Eyes Only Vol. 2: The Fate – limited edition game supplement;
- Delta Green Eyes Only Vol. 3: Project Rainbow – ISBN 1-887797-21-1 – limited edition game supplement;
- Delta Green Eyes Only – 2007, ISBN 1-887797-21-0 – collection of the three Eyes Only chapbooks plus new material;
- Delta Green Scenario: See No Evil in the Unspeakable Oath 16/17
by Fantasy Flight Games:
- Cthulhu Live: Delta Green – ISBN 1-887911-43-X – Live Action RPG supplement.
published online by Dennis Detwiller at 
- Delta Green Scenario: Music From a Darkened Room
- Delta Green Fiction: Through a Glass Darkly
- Delta Green Fiction: Drowning in Sand
- Delta Green Fiction: The Secrets No One Knows
- Delta Green Scenario: Future Perfect
published online at Pyramid magazine:
- Delta Green Article: Green Box [8/21/02 & 10/9/02, with d20 stats]
- Delta Green Scenario: Jack Frost [12/24/99 & 12/31/99]
published in Dungeon 96:
- Delta Green Scenario: PX Poker Night [with d20 stats]
published in Shadis 52:
- Delta Green Scenario: Dia de Los Muertos
- Delta Green: Across the Fence
An unofficial WW2 supplement, under production.
- Delta Green: Our Finest Hour
An unofficial Viet Nam pdf.
Original Wiki source: Wikipedia