Delta Green is a setting for the Call of Cthulhu role-playing game, created by Adam Scott Glancy, Dennis Detwiller, and John Tynes of Seattle gaming house Pagan Publishing.

Premise

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

Publications

As of the beginning of 2005, following Delta Green books were published

Pagan Publishing game books

• Delta Green – the basic sourcebook; February 1, 1997, ISBN 1887797084.
• Delta Green: Countdown – 1999, by John Tynes, Dennis Detwiller and Adam Scott Glancy, ISBN 1-887797-12-2 – the 2000s sourcebook;
• Delta Green Eyes Only Volume 1: Machinations of the Mi-go – ISBN 1-887797-13-0 – limited edition game supplement;
• Delta Green Eyes Only Volume 2: The Fate – limited edition game supplement;
• Delta Green Eyes Only Volume 3: Project Rainbow – ISBN 1-887797-21-1 – limited edition game supplement;

Fantasy Flight Games game books

• Cthulhu Live: Shades of Gray (Fantasy Flight Games, 2000) ISBN 1887911928
• Cthulhu Live: Delta Green – ISBN 1-887911-43-X – Live Action RPG supplement.

Fiction

• Delta Green: Alien Intelligence – March 1998, ISBN 1-887797-09-2 – short stories collection;
• Delta Green: Dark Theatres (fiction anthology, Kruger , 1999) ISBN 1887797173
• Delta Green: The Rules of Engagement (novel, Tynes, 1999) ISBN 1887797165
• Delta Green: Denied to the Enemy by Dennis Detwiller – a novel, set during World War II;

Delta Green