A Hybrid Edition

Achtung! Cthulhu uses the 6th Edition of Call of Cthulhu as its base system. A!C makes a few tweaks to that system, and we shall make some more using elements of 7th edition, Cthulhu by Gaslight and Delta Green: Targets of Opportunity. In essence, we’ll be playing “edition 6.75”.

Character Creation

Character creation is much as presented in the core rulebook, with additional touches from 7th edition and Cthulhu by Gaslight. Full details on the procedure are found here.

Starting with Cthulhu Mythos

If you wish to create an investigator with some pre-existing exposure to the Mythos, you may make a Luck roll. On a success, you start with 1D10 points in the skill. Alternately, you may elect to just take a flat 5 points.

System Mechanics

Although we won’t be using all the new rules from 7th edition, we will be incorporating most of the notable changes, summarized below.

Hard and Easy Rolls

Normally, when making a skill or attribute roll, you will be rolling against the listed value on your character sheet. However, some tasks may be judged particularly Hard or Easy due to outside factors. In those cases you will be rolling, respectively, against half or double your normal value.

Extreme Success

Whenever you roll one-fifth of your effective skill or attribute value, you score an Extreme success. In combat, this usually grants you a special effect, such as bonus damage or an automatic knockout. In non-combat situations, the Keeper may decree that you succeeded with particular aplomb or picked up an extra benefit from your roll.

Pro-tip: To quickly calculate your Extreme success threshold, take the tens value of your skill or attribute and double it. If the ones value is 5 or higher, add one to your final value. For example, a Fieldcraft skill of 40% scores an Extreme success on an “8” or less; if the value were 45-49, then you’d score an Extreme success on a “9” or less.

Pushing Skills

To quote the 7th Edition Quick-Start Rules:

If you can justify it through your investigator’s actions, you can “Push” a failed skill roll. Pushing a roll allows you to roll the dice a second time. However, the stakes are raised. If you fail a second time the Keeper gets to inflict a dire consequence upon your character.

Note that a pushed skill roll does not represent a “free” re-roll. It is literally attempting the skill in a different way. Thus, you have to be able to justify the time and effort that may require, and explain how you are managing to try again.

Combat skills and opposed rolls cannot be pushed, nor can rolls against attributes or derived attributes (such as Sanity or Luck).

Opposed Rolls

The Resistance Table is replaced by the concept of Opposed Rolls. Both parties (typically a PC and the Keeper) roll against the competing skill or attribute and compare results.

A success versus a failure or fumble means the former wins the contest.

If both sides fail or fumble, an impasse has been reached. Depending on the nature of the challenge, a re-roll may be in order.

If both sides succeed, compare levels of success: a roll good enough to beat the Hard threshold beats a “regular” success, while an Extreme success beats Hard and “regular” successes. In all events, a natural roll of 01 always beats every other result. If both sides score the same level of success (for example, both score Extreme successes), compare the value of the skill or attribute being rolled against; the person with the higher value wins. In the event of a tie between those values, the Keeper may declare an impasse or have both sides roll 1D100 until one beats the other with a high roll.

Opposed rolls cannot be pushed.

Bonus and Penalty Dice

Sometimes, the prevailing conditions for the investigators, their environment, and/or the time available to them can hinder or benefit a skill or characteristic roll.

In such situations, the player must take the Bonus or Penalty die which is located in the center of the table and roll it along with his or her usual percentile dice.

The Bonus and Penalty dice are “tens” dice from a percentile set. For a Bonus roll, the player may choose the lower of the two tens dice they just rolled. For a Penalty roll, they must choose the higher of the two tens dice.

Example: Nurse Elizabeth Parrish is trying to staunch the flow of blood on a comrade who has just been shot. Fortunately, she is carrying a medic’s first aid kit. This allows her to make her First Aid roll with the coveted Bonus die. Later, she takes a bad fall through a set of rotting stairs and breaks her ankle. As she had improvidently wandered off on her own, she must attempt to splint her own foot, meaning she must take a Penalty die on this roll. Good luck, nurse!

Bonus and Penalty dice cancel each other out.

“So..what’s the difference between Bonus/Penalty dice and Hard/Easy rolls?”

It’s a thin line, to be sure. Generally, the Keeper will award Bonus or Penalty dice for proactive factors and assign difficulty modifiers for passive factors.

For example, Jen has stated that her character donned a life jacket prior to clambering into the coracle for the storm-tossed crossing to the sea mount out in the North Sea. Although she fails her Pilot (Boat) roll (low to begin with, and further reduced by half when the Keeper ruled this would be a Hard task), and was tossed in the drink, the Keeper decides she can make her Swim roll with the Bonus die. Reverently, she takes down the sacred die and rolls along with her usual trusty percentiles. The results come up “10” and “80” for her two tens dice and a “9” for her ones die. She chooses the “10” to go with that “9” and gets a 19—a success!

Also note that difficulty modifiers are never assigned in Opposed Rolls, but Bonus or Penalty dice may be assigned to represent someone having a distinct edge or disadvantage.

Luck Points

Your Luck attribute serves two purposes.

First, as with older editions, you may be asked to make a Luck roll to avoid an unfortunate fate or fortuitously turn up the right bit of kit or run into the right person at the right time.

Second, you may “spend” your Luck to guarantee success on a skill or characteristic roll! Each point of Luck you burn gives you a +1 to your skill or characteristic value. You may spend Luck after your dice roll, too. So, for example, if you fail a roll by 8 points, you can burn 8 points of Luck and succeed. Or you could spend some Luck to make a regular success an Extreme success instead by raising your skill value and, thus, the threshold for an Extreme success.

The downside, of course, is that your Luck goes down by 1 point for every point you burn. This becomes your new effective Luck value that you must roll against when called on to make a Luck roll.

After each session of play, you may make an Improvement roll for your Luck in the same manner as you would for a checked skill. If you roll higher than your current Luck, you regain 1D10 points immediately.

Rolls that succeed due to Luck point expenditure never result in a skill check.

Pushed skill rolls may not be augmented with Luck points. In effect, on a failed roll you may elect to push or spend Luck—not both.


Characters wishing to add a skill may do so by making the necessary arrangements to find a tutor or take classes. At the end of every four-month period in which sufficient time has been allotted to learning the skill (as per the Keeper’s judgment call), the character may check the skill and make an improvement roll; failing the roll grants 1D10 points in the skill, as normal.

At the Keeper’s option, the interval between improvement rolls may be shortened if the character is immersed in an environment that would promote learning. For example, learning a foreign language goes considerably faster if the character is living in an area where the language is spoken all the time. Picking up skill in a firearm tends to happen pretty quickly in war zones. And so forth.

It is the player’s responsibility to track their time intervals.


We will be implementing 7th edition’s slightly more “narrative” Sanity rules, briefly outlined here:

  • Regardless of whether any points are lost, failing a Sanity roll always causes the investigator to lose self-control for a moment, at which point the Keeper should choose an involuntary action for the investigator, such as jumping in fright, crying out, taking an involuntary combat action, etc.
  • A fumbled Sanity roll means the investigator suffers the maximum possible SAN loss.
  • Sanity loss is measured per encounter, not per source. Thus, seeing a single ghoul or a roomful of ghouls carry the same potential SAN loss of 0/1D6. Also, as before, there is a finite limit to the SAN you can lose from seeing the same creature equal to the maximum potential loss—thus, after you’ve lost 6 SAN from encountering ghouls (even if that’s over multiple encounters), you can’t lose any more points. There is a space on your character sheet for keeping track of this (“Creatures Encountered”)—be sure to use it!
  • When you go insane (see below), regardless of whether your insanity is temporary or indefinite, the same procedure is followed:
    • You suffer a “bout of madness”—hand over your character sheet to the Keeper, who may add an interesting amendment to your Personal Data or History on page 2 of your character sheet. If you are in the presence of other (lucid) investigators, your madness will last 1D10 combat rounds, but may take the form of presenting a danger to yourself and your comrades. If you are alone, your madness will last longer (typically hours) and will usually end with the Keeper describing you regaining your senses in a different location, perhaps with evidence of what you did in the intervening time splattered all over you…
    • After you recover your wits, you will still be subject to an Underlying Insanity. This lasts 1D10 hours in the case of Temporary Insanity, or until you are successfully treated and cured in the case of Indefinite Insanity. While suffering from an Underlying Insanity, you are still in full control of your character and may act normally. However, losing even a single point of Sanity will re-trigger your original “bout of madness”. There is no limit to the number of times this can happen. Furthermore, the Keeper may integrate your bout of madness into your normal life via phobic or manic reactions, or alternately by providing unreliable descriptions of people and places. In the latter situation, if you feel the Keeper is trying to fool you, you may attempt a “reality check” by rolling against your current SAN value. Success means the Keeper must describe what is genuinely in front of the investigator; failure, however, triggers another bout of madness, so use your reality checks wisely!
  • As in older editions, Temporary Insanity is triggered by the loss of 5 or more points of SAN in one roll (and the subsequent success on an Idea roll) while Indefinite Insanity kicks in after the investigator loses one-fifth of his current SAN value in the course of a day. A “day” in this instance is defined by the Keeper, usually lasting until the investigator reaches a place of safety in which they can rest and recover their wits. Depending on the situation, it may mean surviving until dawn, sitting down for a nice cup of tea, or having a good night’s sleep. Note that under front-line combat conditions, a “day” may last for considerably longer than 24 hours, vastly increasing the odds of “cracking up.”
  • As in older editions, suffering a bout of madness from a Mythos source grants +5 to Cthulhu Mythos the first instance and +1 each time thereafter.
  • Recovery from Indefinite Insanity is possible with one-on-one psychiatric care or commitment to an institution. Also, if the investigator survives until the end of a “chapter” in the campaign (i.e. when everyone makes skill improvement rolls), he or she is judged to have largely recovered and no longer suffers from an Underlying Insanity.
  • Sanity points may be regained through Keeper award, through psychotherapy sessions, by advancing a skill to 90% or higher, or by spending time with a person marked on the “Family & Friends” section of the character sheet. In the latter case, the player must describe how they are spending time with their loved one and how this is helping them recover. They then make a Sanity roll: success grants 1D6 points of SAN, while a failure costs 1 point and fundamentally alters the investigator’s relationship with that family member or friend.
    • Players should choose one of their family or friends to be a “key connection”—mark the name with an asterisk so you don’t forget. When spending time with your key connection, you may roll a Bonus die when making your Sanity roll to recover SAN. (This is an exception to the rule that Sanity rolls cannot be modified with Bonus or Penalty dice.)
  • When an investigator’s Cthulhu Mythos skill rises above the value of his or her Sanity score a turning point has been reached. That investigator’s understanding of the universe undergoes a paradigm shift that results in a permanent change to their personality and comprehension of their place in the cosmos. How this is portrayed is left open to the player. The player may decide that his or her investigator’s mind is inured to the horror, no longer cares, or has a more profound understanding that is no longer shaken by the truth. From that point onward, all SAN loss is halved. Once this change has taken place it is permanent and will not revert if the investigator’s Sanity should rise above their Cthulhu Mythos knowledge.

A Hybrid Edition

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