Running a Delta Green-campaign – Part Three

Welcome to the third post about creating and running a Delta Green-campaign. In the first post I presented the general concept and in the second post I discussed investigation and types of clues. In this post I will discuss the rules, and why they were they chosen.

Picking the Rules

The Basic Roleplaying of Call of Cthulhu, The Gumshoe of Trail of Cthulhu or the Next Gen BRP from Unknown Armies?

CoC has an awful lot of skills, often with small values and often of no use during the game. Unknown Armies is a lot more tight, but neither the magic system nor the madness system fits into the Cthulhu Mythos, though otherwise very interesting. The pool-based system of Gumshoe is not, what I want, though the sanity-system is very promising.

In the end I wound up using the skills and combat rules from Unknown Armies and the Sanity mechanic from CoC.

Basic elements of the Rules

Each character consists of four abilities and to each ability belongs a category of skills, so if you lack a particular skill, you default to the ability. Defaulting lessens the degree of success. From the abilities (which are bought) are derived sanity points and health points.

A skill check is done by rolling less than the skill with percentile dice. Rolling above the skill but below the ability score results in a minimal success. Rolling doubles causes extra effects to happen, and whether this is beneficiary or not depends on whether the roll is a success or a failure.

The Specialized Rules

These are house rules that support themes and play style. We have several of these, and they push the play into different directions. I have covered most of the house rules in separate posts.

Decline points

Mechanic that allows the character to survive an otherwise lethal Cthulhu Mythos encounter. Once out of points, the fate of the character is sealed, and any random mishap may at any time eliminate the character – he is out of fate or luck. But new points can be bought.

Humanity points

These points can be spent to restore sanity points, reset traits or by new decline points. To earn them, you play relation-scenes, and to buy new Decline points, you burn your relations.

(Decline and Humanity points are detailed in this post)


Each mission usually begin with a relation-scene for each character. Each player takes turn to set the scene or narrate it. As the GM I never participate in these scenes, and all NPCs are played by the other players. These scenes never develop the plot of the mission, but let the characters grow – and when the player needs to buy new Decline-points, the player must burn a relation. These become hard and meaningful choices due to the build-up through relation-scenes.

(Relation-scenes are detailed in this post)

Agent Points

After each mission each character earns an Agent-point. These are spent to buy specialized equipment (we are lazy, when it comes to character economy), contacts and episodes. Buying equipment: Any trivial piece of equipment is always available, when the agents go on a mission, and obvious equipment is always carried by the agents even without stating it – e.g. a flashlight is always carried. However special equipment, high quality or exotic equipment must be bought, but can be introduced almost instantly – e.g. a player can spend points to state, that in the trunk of the car is a sniper rifle, he swiped a while ago.

Contacts: Players can spend points to introduce contacts, that can help them with their missions. Contacts can open doors, find witnesses and otherwise help the agents with intel and the like.

Contacts and equipment costs one or more points. The exact price is negotiated between player and GM.

Missions: The players can pay three points, and this allows them to buy the next mission. After each mission I ask the players, if any of them wants to buy the next mission. If so, then I plan with the player the details of the mission – where, when, how and how the mission is obtained. The GM still does the final work, so even the buying player is still in for a mystery.

(Agent Points are described in details in this post)


Each agent has three traits. These can be activated each once per session, and they allow the player to flipflop the roll, i.e. switch the numbers on the percentile roll, 92% becomes 29%. The player picks a trait and describes how it influences the roll.

Each trait can either be a positive or a negative trait, and independently of this, it can either be used positively to flipflop the roll, or it can be used negatively to earn a fortune point. A player can pay Humanity points to re-activate a spent trait, so it can be used an extra time for flipflops.

Fortune Points

Fortune points are used to transform critical failures to regular successes. A critical failure is when the skill check is failed, and the dice come up a double like 77, 88 and 99. The points don’t work on regular failures.

To gain a Fortune point a player must choose to use his trait against him by granting himself a penalty of 30% to the skill check. This can be done any number of times.

Corrupted Traits

When a character looses 5 points in one go or 20% and becomes eligible for an insanity according to the regular Sanity-rules of CoC, then one of his traits can be corrupted. GM and player negotiates, they pick a trait, and writes a corrupted trait next to it (e.g. curious becomes obsessed). Whenever the player wants to do a flipflop, he will be basing it on the corrupted version instead of his normal trait. For flipflops the difference between traits and corrupted traits is purely color. However a corrupted trait can also be used negatively, and instead of earning a Fortune point, the player earns an Insight point.

Insight Points

An Insight point can be spent, when casting a spell. Each spell costs sanity points – and this is instead of CoC’s Magic Points and Power – and each Insight point covers 5 sanity points. An Insight point thus allows an agent to cast spells for no or a minimum cost of sanity.

(Traits, Corrupted Traits, Fortune Points, and Insight Points are covered here)


Each character must have three types of threats. A threat represents something that will hinder the continued presence of the character in the campaign. The threats represent not necessarily something that will kill the agent, but some element that will force the agent to cease working for Delta Green. The first level is some personal element, for instance alcoholism, and the second level comes from the immediate surroundings, such as family, friends and career. The third level is tied to the story arc, and represents foes that may appear, whenever the agents makes too much noise. In our campaign it is The Men in Black, who may appear, if the agents cause too much mayhem. The Men in Black can also appear as a specific part of the mission.

(Threats are detailed here)

Creating Leads

For 5 sanity points a player can define a link between two facts. In other words a player can construct a connection between two clues, that otherwise does not exist, but becomes real once defined. This represents the curious omnipresence of the Mythos and its non-causal way of being connected, that can be understood by people, whose rational mind is slowly corroding. It also allows the players to connect dots in new and exciting ways and allow them to move faster through their agents’ investigation.

(Creating Leads described here)

Synergies – A Comment on the Rules

One element the rules do is to push the game. The agents are efficient, when they use their traits to flipflop their skill checks. The traits are chosen by the players, but once sanity is lost a trait becomes corrupted, and in order to employ the powerful benefits, you need to draw on the corrupted element thus steadily reminding the player of the growing insanity of the agent. Secondly once sanity is lost, a new door opens, as the player can gain Insight points, allowing the agent to cast spells without loosing sanity – so the loss of sanity gives access to spell casting. Likewise there is a relation between Decline and Humanity points.

Next up is the structure of the campaign.


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