Call of Cthulhu vs Delta Green

The short answer

Pick Call of Cthulhu if you want to play an ordinary person in 1925 who reads the wrong book and cannot unread it. A librarian, a country doctor, a dilettante with a train ticket. It is the older and broader game, built for period investigation, and it carries the deepest library of published campaigns in the hobby.

Pick Delta Green if you want to play the people the government sends when somebody else reads that book. You have a badge, a cover story and a partner at home who has started asking where you go at night. The horror is not only what you find, but what you are ordered to do about it.

What these two games have in common

They share a bloodline. Delta Green began in 1992 in the fanzine The Unspeakable Oath, became a Call of Cthulhu supplement from Pagan Publishing in 1997, and only stood on its own in 2016 with Arc Dream Publishing's Agent's Handbook. The engine underneath is the same: the percentile system Chaosium built for Basic Roleplaying and first used in Call of Cthulhu in 1981. Every skill is a number, you roll d100, and you want to roll under it.

Both are investigation horror, not monster hunting. You are there to find out what the thing is and then live with knowing. Both track Sanity as a score that falls quickly and climbs slowly. Both hand the table one referee with a name of their own: the Keeper in Call of Cthulhu, the Handler in Delta Green.

Where they really differ

The era decides who you are. Call of Cthulhu defaults to the 1920s, and that is not set dressing. No telephone in your pocket, no records check, two days on a train between the clue and the answer. Your investigator is an amateur with a hunch and a library card. Delta Green is set now, with databases, warrants and a federal budget behind you, and none of it saves you, because the thing you hunt has grown into the system you work for. You are not exposing the conspiracy. You are the conspiracy.

Sanity has an address in Delta Green. Both games take Sanity off you. Delta Green also asks who else pays. Every agent has Bonds, the people who keep them human, and each Bond is a number. When trauma lands you can push part of it onto a Bond: the Sanity loss shrinks and the Bond drops by the same amount. Do that a few missions running and your marriage is a 2. Between operations your agent gets a home scene and picks one use for the time, and nearly every choice costs a Bond point somewhere. You are not spending hit points. You are spending the people who would notice if you disappeared.

You can get used to it, and that is the trap. Delta Green sorts Sanity loss into violence, helplessness and the unnatural. Take violence three times without breaking and your agent becomes adapted: bloodshed stops costing Sanity. He pays once, in Charisma and in every Bond he has, and afterwards he is calm at the scene and sleeps fine. Nobody at home recognises him.

Call of Cthulhu leaves more room to survive a bad roll. The seventh edition, which appeared in 2014 and reached wide print in 2016, added cushions. You can push a failed roll by describing how you try differently, at the price of a worse consequence if you fail again. Bonus and penalty dice replace modifier tables. Luck is a pool you spend to nudge a near miss into a success. Delta Green offers none of that. Its guns use a Lethality rating: roll d100 against that number, and under it the target is simply dead.

The preparation is a different kind of work. Running Call of Cthulhu well means homework about a period: what a long distance call cost in 1923, what a woman could do on her own authority, how long a crossing took. Delta Green asks almost no history, because the setting is outside your window, but it does ask you to prepare the paperwork and the lie: which agency your agent answers to, what the cover story is, what happens when the local police want a name. Lighter for some tables, harder for others.

Campaigns have a different shape. Call of Cthulhu spans a single evening up to Masks of Nyarlathotep, which runs a year or more across several continents. Delta Green thinks in operations: a mission of two to four sessions, then a home scene, then the next mission. The campaign is the erosion you watch happening in the gaps.

What it feels like at the table

Call of Cthulhu: it is 1926 and you are in a county archive with a clerk who wants to close up. You fail your Library Use roll, push it by announcing that you will take the whole box of deeds back to the hotel, and now you are in a taxi with stolen county property on your lap. Three sessions later the horror arrives quietly: the name signing the 1874 deed is the name in yesterday's hotel register.

Delta Green: the operation is over. The thing in the crawlspace is dead, or gone, or was never entirely there, and you burned the house because burning it was the only option anyone offered. Now it is Tuesday evening, your agent is at a kitchen table, his wife asks an ordinary question about the weekend, and you decide whether to lie to her again. The most frightening roll in Delta Green is the one you make at home.

What you actually need to buy

For Call of Cthulhu, one book runs everything. The Call of Cthulhu Keeper Rulebook costs 44.95 euro and holds the rules, the bestiary, the spells and starting scenarios. Players need no copy of their own. The Investigator Handbook at 39.95 euro is the optional player book, with expanded character creation, occupations and a primer on the 1920s. The Call of Cthulhu 50th Anniversary Slipcase at 109.95 euro gathers both books plus the Keeper Screen Pack.

For Delta Green the entry point is the Delta Green Agent's Handbook at 39.95 euro, which carries the complete rules of play: agent creation, skills, combat, Sanity, Bonds, home scenes and agency dossiers. A Handler can run a published operation from that book alone. The Handler's Guide at 59.95 euro is the setting book rather than a requirement: the secret history, the unnatural entities and the rival conspiracy. The Delta Green RPG Slipcase at 99.95 euro puts both hardcovers in one case.

Choose Call of Cthulhu if ... / Choose Delta Green if ...

Choose Call of Cthulhu if your group enjoys research, maps and period detail. If you want a campaign you can run for a year without writing it yourself, because Masks of Nyarlathotep and Horror on the Orient Express already exist. If your players are new to roleplaying: one book covers the table, and pushed rolls and Luck give a beginner a second chance. If you want the horror kept at arm's length, in 1925, where it cannot look like your own street. And if your group would rather punch a cultist than write a report, take Pulp Cthulhu.

Choose Delta Green if you want a modern setting where the phone works, the lab results come back, and none of it helps. If your players want their character to change across a campaign and are willing to watch that change be a decline. If you prefer short, tense operations to a year-long plot. If your table can handle colleagues who lie to each other. And if you want combat quick and dangerous, where one Lethality roll ends an agent who did everything correctly. Say that out loud before session one: the game is built to take your agent apart.

Where to start at Netherbook

One book each and you are playing. For Call of Cthulhu that is the Keeper Rulebook, for Delta Green the Agent's Handbook. If you want to read a little further first, we keep a Call of Cthulhu starter guide and a Delta Green starter guide on the site.

After that, the two collections show what a campaign can grow into. The Call of Cthulhu collection holds the great campaigns and the other eras, from Berlin: The Wicked City to Cthulhu by Gaslight. The Delta Green collection holds the operations, from The Labyrinth to Impossible Landscapes. Buy the core book, run one scenario, and both games will tell you inside three hours whether they are yours.