The AGENT'S HANDBOOK is a players-only rulebook for Delta Green: The Role-Playing Game. This new incarnation of the award-winning DELTA GREEN game line includes:

* Rules for creating agents of all types.
* Rules for tense, fluid investigations. Players who use their agents' skills in clever ways have the best chance to succeed -- and survive.
* Nerve-wracking rules for combat, where random disasters can undo the most careful planning.
* Mind-melting Sanity rules that see agents gradually deteriorate -- and sometimes snap.
* Rules for "home" scenes where players see what their agents are fighting for.
* Quick, intuitive rules to determine equipment and assets.
* Dossiers on the federal agencies most likely to be featured in play.

Delta Green: Agent's Handbook

Roll20

Foundry VTT

Dennis Detwiller

Simeon Cogswell

Obviously this will vary from table to table, but here are some good places to start! If your game is played in person, most likely you will want to get a set of dice, something to write with, and paper to take notes. If your game is hosted online instead, you will probably need to make accounts on a few sites for things like character sheets, access to the Virtual Tabletop for maps and tokens, and sites like Discord or Zoom for video/voice calls during the session. You won't always need to have the rulebooks to start, but if you want to read through them to make sure you know all the rules, this might also be a good option.

What supplies do I need to play Delta Green?

Delta Green uses four-sided, six-sided, eight-sided, ten-sided, twelve-sided and twenty-sided dice.

While many people think Delta Green is inspired by the X-Files, creator Dennis Detwiller has said that isn't true. While he thought the X-Files was an OK show, it wasn't a main source of inspiration for the game. He has cited other movies like The Exorcist, Faust, The Fog, Jacob's Ladder, Salem's Lot, The Shining, and The Thing as major influences on him and his work.

Tabletop Roleplaying Games can cover an impressive range of topics and styles, including violence, horror, romance, and many many more! However, if there are specific themes or content that you’re uncomfortable with, let your group and GM know before the game, and have an open conversation about these topics. Any group worth playing with should be respectful and understanding of your concerns and the game can be adjusted so everyone is having fun. Many tables also use “Safety Tools” which help ensure that these conversations are handled easily, and everyone has a voice at the table.

What if I'm not comfortable with themes or topics in Delta Green?

D20 Live walks you through a quick (and very comedic) breakdown of how Delta Green works, include stats, bonds, and combat.

How to Play Delta Green

Daniel Profeta provides an indepth look into Delta Green, walking you through everything you might need to know to start on your Lovecraftian horror journey!

A Deep Dive Into Delta Green

I'm going to take a risk and put Delta Green's biggest flaw up front: like many TTRPG systems on the market right now, it trades on the strength of its setting more than making major innovations in game design. If you know Call of Cthulhu or any of the other BRP-based games out there, you won't find very much to surprise you; minor tweaks make combat faster (and even more deadly, if that's possible) and the Bonds system is good enough to steal for other TTRPG systems.

Again, where Delta Green shines is in its setting, themes, and style. Every page absolutely drips with atmosphere, and the way it treats the Lovecraft mythos is unlike anything else. Where Call of Cthulhu shares its sense of slow-burning investigation punctuated by brutal violence, Delta Green injects a sense of realism by putting you in the shoes of a person you could meet at Starbucks. Where D&D and similar games give you the chance to slay the monster, the best you can hope for in Delta Green is to cover up the monster's tracks. 

Delta Green is different from any other TTRPG you'll ever play. There are no easy answers, no big victories, and no comfortable space between yourself and your character. If you're a fan of the X-Files, True Detective, or Annihilation; and if you have a strong stomach and an urge to plumb the extremes of human experience, then give it a try!

It's Call of Cthulhu, but in the modern era, with more competent PCs, No longer "just a guy off the street" — your PC is someone who is coming into the Mythos-busting world with some skills that might keep them alive for an extra five minutes! You're no pulp hero, but you won't get crushed by the first cultist you meet, either!

The game uses a percentile system that's easy to grasp, and the skills are very obvious. The best element of the game is the Bonds system. Unlike Call of Cthulhu, where your Sanity feels like a variation of HP, Bonds are actual relationships your PC has with others that can take damage as you deal with the horrors of magic, murder, and the Mythos. Rather than just lose 5 points of Sanity, you can offload that loss to a Bond, which from a role-playing standpoint, can introduce all sorts of troubles for your PC when they're back home or at their day job. 

The biggest challenge a GM will have with Delta Green is finding ways to prevent players from, in character, using the Internet to solve problems and answer questions.

For years, I was deeply invested in Call of Cthulhu. It was my go-to system for cosmic horror, and I saw no reason to deviate. Delta Green was always on my radar, but I stuck with what was familiar—until a friend begged me to try it. I relented, and now, I only wish I had checked it out sooner. Delta Green isn't just a variation of Call of Cthulhu; it's a marked improvement in nearly every way, from mechanics to storytelling.

Streamlined Mechanics for a Faster, More Tactical Experience:

The mechanical changes in Delta Green refine and enhance the investigative horror experience. The system trims down extraneous stats and skills, making character sheets more intuitive. The changes may seem minor at first glance, but they result in a more streamlined character creation and gameplay experience.

Combat is vastly improved. Instead of Call of Cthulhu’s sometimes-clunky bonus and penalty dice, Delta Green applies simple +/- percentage modifiers, reducing unnecessary rolls and keeping combat fast and deadly. And then there’s the lethality system—an absolute game-changer. Automatic weapons, explosives, and heavy ordnance work seamlessly with this mechanic, making high-powered combat frighteningly efficient.

Sanity mechanics have been vastly improved as well. No more rolling on a chart for temporary insanity or fumbling to assign a phobia. Instead, Delta Green distills the moment of breaking down into a clean and effective fight, flight, or freeze response. Long-term mental degradation is represented by breaking points, where accumulated trauma permanently alters an agent. The game separates sanity loss into three categories—Violence, Helplessness, and the Unnatural—with clear guidance on how mundane horrors impact an agent’s psyche, something I always felt was vague in Call of Cthulhu.

Perhaps my favorite new sanity mechanic is adaptation. With enough exposure, agents can become numb to Violence and Helplessness, but at a terrible personal cost. Watching a player realize their character has lost some key part of their empathy, self-determination, and/or humanity is a gut-punch every time.

And then there’s Bonds—an elegant, tragic mechanic that forces players to choose between preserving their own sanity or their relationships. Every potential sanity loss presents a terrible dilemma: suffer the mental strain yourself, or push that burden onto your loved ones and watch your personal life crumble. It's an outstanding evolution of Call of Cthulhu’s simplistic “key background connection” mechanic, reinforcing the deeply personal horror of Delta Green.

The Narrative - A Perfect Blend of Cosmic Horror and Conspiracy:

Delta Green drips with atmosphere. Whether you're running the classic 1990s setting or the modern incarnation, the game thrives on its fusion of government conspiracy and cosmic horror. Your agents aren’t just uncovering eldritch threats—they’re responsible for covering them up. The ethical dilemmas pile up fast, and unlike Call of Cthulhu's investigators, Delta Green agents must wrestle with the terrible things they do in the name of national security.

Every classified crime committed takes its toll. Every innocent killed “for the greater good” haunts the agents responsible. Delta Green doesn’t let you be a detached observer of the cosmic horror; it forces you into the role of someone making terrible choices for the right reasons. The personal costs are immense: agents lose their jobs, destroy their marriages, drink themselves into oblivion, and sometimes, they choose to take their own life when nothing else is left. Delta Green is about tragedy, sacrifice, and the slow erosion of everything good in an agent’s life—and it makes those rare victories against the Unnatural feel truly meaningful.

The lore is phenomenal, packed with plot hooks, handouts, and a rich history I can’t begin to discuss without massive spoilers. But if you want to experience Delta Green at its best, avoid spoilers at all costs. Don’t read the fiction first. Don’t listen to actual plays. The magic of Delta Green is discovering its horrors through play. Once you experience something like Impossible Landscapes or God’s Teeth, you’ll never forget it. But if you spoil yourself beforehand, you’ll forever regret it.

Final Verdict:

Delta Green is a massive step forward from Call of Cthulhu, both mechanically and narratively. If you love horror RPGs and you haven’t tried it yet, don’t wait—this game is a modern masterpiece. Whether you want to run high-intensity investigations, grim psychological horror, or a deeply personal tragedy of self-destruction, Delta Green delivers. Just be prepared to lose yourself in the darkness.

DG is great and provides all the fun of Lovecraftian horror settings with vast government conspiracies and finicky gun fondling. But, what it adds in complexity and attention to detail just makes the world seem all the more real and dangerous. It's essentially Call of Cthulhu with players who have greater access to firearms and training. the world is still just as dangerous, if not more so

Delta Green

Born of the U.S. government’s 1928 raid on the degenerate coastal town of Innsmouth, Massachusetts, the covert agency known as Delta Green opposes the forces of darkness with honor but without glory. Delta Green agents fight to save humanity from unnatural horrors—often at a shattering personal cost.

In Delta Green: The Role-Playing Game, the players are those agents. They fight to keep terrors from beyond space and time from infecting the world and claiming human lives and sanity. The Handler is the game moderator who creates and interprets their world, presents the unnatural horror that they investigate, and describes the awful aftermath of their sacrifices.

Originally created by Dennis Detwiller, Christopher Gunning, Shane Ivey, Greg Stolze

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Professions

You study humanity. You’re concerned with the patterns that emerge over time, across land masses, cultures and language groups. You might be a number cruncher, a field worker trudging through the jungle, a “human terrain” expert in a war zone, or a think tank analyst sifting myth from history in reports of the Tcho Tcho peoples.

Anthropologist or Historian

Computers and machinery are the backbone of modern industry. You are a craftsman with data or machinery, possibly for the government, most definitely for profit. However you use your skills, the overlap between information technology and awareness of the unnatural could make this the most dangerous job on the planet.

Computer Scientist or Engineer

Most Delta Green agents are federal law enforcement officers, mostly from the FBI. Delta Green decided long ago that federal agents have the optimum balance of skills and mental stability needed to confront the unnatural.

Federal Agent

Doctors are often the first to uncover signs of an unnatural incursion, and the most valuable investigators of its disastrous effects on humanity.

Physician

You expand human knowledge in a field such as biology, physics or chemistry. In theory, you form a hypothesis, build an experiment to test it and see if it survives. When certain forms of knowledge cause
insanity and death, it’s easy to conclude that some hypotheses should not be tested.

Scientist

A soldier usually finishes training and settles into a specialty until their contract is up. You’ve volunteered for a more difficult path. As a member of a group like the U.S. Army Special Forces, the SEALs, the USMC Critical Skills Operators, or the CIA Special Operations Group, you’ve spent years in the most grueling training on the planet, and now serve on the most dangerous missions around