Roll 1d100. The result must be equal to or under the relevant skill or characteristic value to succeed.
The Keeper sets a goal before the roll, then determines which skill applies. Only roll when the outcome is uncertain and the stakes matter.
Result
Roll requirement
Notes
Critical Success
01
Something extra-beneficial occurs
Extreme Success
≤ Skill ÷ 5
Masterly, on the edge of what is possible
Hard Success
≤ Skill ÷ 2
Skilled, competent execution
Regular Success
≤ Skill
Goal fully achieved
Failure
> Skill (not fumble)
Goal not achieved; may push the roll
Fumble
96–100 (skill <50) or 100 (skill ≥50)
Worst possible outcome; cannot be pushed
Difficulty Levels (Opposed / Tasks)
Regular: Roll ≤ full skill value. Used for most tasks.
Hard: Roll ≤ half skill. Opponent skill 50–89, or clearly difficult.
Extreme: Roll ≤ skill ÷ 5. Opponent skill 90+, or on the edge of possibility.
In opposed rolls (melee, social), both sides roll. Compare success levels; higher level wins. Ties go to the attacker. No difficulty levels in opposed rolls — use bonus/penalty dice instead.
Opposed Success Levels
Level (highest wins)
Rank
Critical
6 (best)
Extreme
5
Hard
4
Regular
3
Failure
2
Fumble
1 (worst)
Bonus & Penalty Dice
Roll two d10 tens-digits along with the units die.
Bonus die: Take the lower tens digit (gives better chance).
Penalty die: Take the higher tens digit (gives worse chance).
Example with Skill 55, bonus die: Roll tens 3 & 7, units 4. Two results: 34 and 74. Take 34 (lower) → success! Without bonus, result would have been 74 → failure.
Pushing the Roll
After a failure (not a fumble), the player may attempt the roll a second and final time by describing extra effort, risk, or approach.
Player must justify the push ("I throw myself at the door with full weight...").
If the pushed roll fails, the Keeper applies serious consequences.
Fumble on pushed roll: Keeper has free rein over outcome.
Push = raising the stakes. Foreshadow the consequences before the player decides to push!
Luck
The Keeper may call Luck rolls for external circumstances (not skill-based).
Spending Luck (optional rule): After a failed skill roll, spend Luck points 1-for-1 to reduce the roll result. Cannot spend Luck on Luck rolls, Sanity, damage, or combat rolls.
Cannot spend Luck on a pushed roll (choose one or the other).
Criticals, fumbles and firearm malfunctions cannot be bought off with Luck.
Recovering Luck: After each session make an improvement check (roll above current Luck score on 1d100 → gain 1d10 Luck). Max 99.
Derived from STR+SIZ: ≤64 = −2, 65–84 = −1, 85–124 = 0, 125–164 = +1, etc.
MOV
Base 8 (human); reduced with age
Experience & Improvement
Tick a skill box when you use it successfully during play.
At end of scenario/chapter: roll 1d100 per checked skill. If roll > current skill, gain 1d10 to that skill.
No tick if bonus die was used; no tick for Cthulhu Mythos or Credit Rating.
If skill reaches 90%+, gain 2d6 Sanity at development phase.
Luck also makes an improvement check at end of each session.
Dice Roller
d100 Skill Roll
—
—
Other Dice
Roll History
No rolls yet.
Quick Reference: Skill Values
Skill %
Regular (≤full)
Hard (≤½)
Extreme (≤⅕)
Fumble
Investigators
Track HP, SAN, Luck and MP. Data saved automatically.
No investigators yet. Click "Add Investigator" to begin.
Combat Reference
Initiative & Order
Default: Act in DEX order, highest first.
Readied firearms fire at DEX + 50 in the order.
Ties broken by DEX value; if still tied, by combat skill.
Optional Initiative Roll: Each character makes a DEX roll; sort by success level (Extreme first, then Hard, Regular, Fail). Ties broken by DEX.
Establish initiative at the start; new combatants make a DEX roll and slot in.
One action per round: Attack, Dodge, Maneuver, Flee, First Aid, or use an item. Social skills (Fast Talk, Persuade) also cost an action.
Melee Resolution
Attacker rolls their Fighting skill.
Defender chooses: Fight back (own Fighting) or Dodge.
Higher success level wins and deals damage; ties go to attacker.
If defender wins the opposed roll, they deal damage to the attacker instead.
Outnumbered: After one fight-back/dodge, all subsequent attacks on that character gain a bonus die.
Firearms
Not opposed — Keeper sets difficulty by range.
Within base range: Regular; Long (2x): Hard; Very long (4x): Extreme.
Point-blank (DEX/5 feet): +1 bonus die.
Aiming (delay one round): +1 bonus die.
Diving for cover (Dodge roll required): attacker gets penalty die; diver forfeits next action.
Wounds & Damage
Major Wound: Single hit deals damage ≥ half max HP.
Character falls prone immediately.
Make CON roll or fall unconscious.
If HP reaches 0 while Major Wound is marked → Dying.
Dying (0 HP + Major Wound):
Unconscious. Make CON roll at end of each round or die immediately.
Only First Aid can stabilize; Medicine cannot be used until stabilized.
Successful First Aid → gains 1 HP; make CON roll per hour (not round).
0 HP, no Major Wound: Unconscious; will heal naturally (1 HP/day).
Damage > max HP in one hit: Death inevitable.
Other Damage
Severity
Damage
Examples
Minor
1d3
Punch, mild acid, small fall (per 10ft onto swamp)
Moderate
1d6
Club, strong acid, drowning/round, small bullet, fire torch, fall onto grass
Severe
1d10
.38 bullet, axe, flamethrower, fall onto concrete, grenade (6–9 yds)
Deadly
2d10
Hit by car (30 mph), grenade (3–6 yds), strong poison
Terminal
4d10
Speeding car, grenade (<3 yds), lethal poison
Splat
8d10
Head-on collision, hit by train
Healing
Regular damage: 1 HP per day (no major wound box ticked).
First Aid: Within 1 hour; grants 1 HP. May attempt once (2nd attempt = Pushed roll).
Medicine: Any time after injury; restores 1d3 HP. If not same day: Hard difficulty. Cannot stabilize dying without First Aid first.
Major Wound recovery: CON roll each week. Success: 1d3 HP; Extreme success: 2d3 HP. Bonus die for rest + medical care. Major Wound clears when: Extreme CON roll, or HP ≥ half max.
Fighting Maneuvers
Used to disarm, restrain, trip, push, or similar (not just deal damage).
Compare Build (derived from STR+SIZ). If attacker Build is 3+ lower: impossible. 2 lower: 2 penalty dice. 1 lower: 1 penalty die.
Resolved as a normal Fighting roll vs. target's Dodge or Fighting.
Successful maneuver: disarm, impose penalty die on opponent, grant bonus die to allies, or similar one-time effect.
Sanity
Sanity Rolls
Roll 1d100. Success = roll ≤ current Sanity score.
Success: Lose the lower (or zero) amount listed.
Failure: Lose the higher amount listed.
No bonus or penalty dice on Sanity rolls (exception: Self-Help).
Luck cannot be spent on Sanity rolls.
Sanity Caps
Starting SAN: POW × 5
Maximum SAN: 99 − Cthulhu Mythos skill
Each point of Cthulhu Mythos skill permanently reduces max SAN by 1.
SAN can never exceed max SAN, no matter what.
Sanity 0 = permanently insane; becomes an NPC.
Insanity Thresholds
Temporary Insanity: Lose 5 or more SAN in a single roll/round. Brief bout of madness (hours-long), followed by underlying instability.
Indefinite Insanity: Lose 1/5 or more of current SAN in one session. Longer, deeper instability. Prone to further bouts.
Permanent Insanity: SAN reaches 0. Character becomes an NPC.
A bout of madness begins the insanity. The Keeper may temporarily take control of the character, or generate a random bout from the tables. The bout is followed by an underlying period of instability.
Recovery
Temporary: Recover after a rest or Psychotherapy (INT roll; on success, Keeper determines what is remembered).
Indefinite: Requires professional therapy over time; Psychotherapy roll at end of each session of real-world time. Recover 1d3 SAN on success.
Self-help: Spending time with a Significant Connection (from backstory) at investigator development phase can restore SAN.
Skill mastery: Reaching 90%+ in a skill restores 2d6 SAN at development phase.
Mythos Sanity Loss Table
Entity / Encounter
SAN Loss (Success / Fail)
Fresh corpse
0 / 1
Seeing someone die horribly
0 / 1d3
Cultist ritual
0 / 1d3
Ghoul
0 / 1d6
Deep One
0 / 1d6
Mi-Go
0 / 1d6
Byakhee
0 / 1d6
Serpent Person
0 / 1d6
Dark Young of Shub-Niggurath
1d3 / 1d8
Dimensional Shambler
1d3 / 1d10
Night-Gaunt
0 / 1d6
Hunting Horror
0 / 1d8
Shoggoth
1d6 / 1d20
Star Vampire
1d3 / 1d10
Great Race of Yith
0 / 1d6
Flying Polyp
1d3 / 1d10
Elder Thing
0 / 1d6
Outer God (e.g. Nyarlathotep)
1d6 / 1d20
Great Old One (e.g. Hastur)
1d6 / 1d20+19
Seeing Cthulhu
1d6+6 / 1d10+20
SAN loss entries are per encounter, not per individual creature seen. Roll once for the encounter regardless of how many are present.
Sample Phobias (Temporary/Indefinite)
Roll 1d20 or choose:
d20
Phobia / Mania
1
Agoraphobia (open spaces)
2
Claustrophobia (enclosed spaces)
3
Xenophobia (strangers/outsiders)
4
Nyctophobia (darkness)
5
Zoophobia (animals/insects)
6
Necrophobia (dead things)
7
Pyrophobia (fire)
8
Thalassophobia (deep water/ocean)
9
Paranoia (being watched/followed)
10
Religious mania (obsessive devotion)
11
Kleptomania (compulsive stealing)
12
Pathological lying
13
Obsessive-compulsive ritual behavior
14
Dissociative fugue (wandering blackouts)
15
Megalomania
16
Catatonia (paralysis under stress)
17
Hysterical blindness/deafness
18
Amnesia (session events erased)
19
Multiple personality disorder
20
Keeper's choice or roll again
Mythos Knowledge Effects
Reading a Mythos tome: Gain Cthulhu Mythos skill; suffer SAN loss.
Witnessing a ritual or spell: Possible SAN loss + Cthulhu Mythos gain.
Each Cthulhu Mythos point gained permanently lowers max SAN by 1.
Cthulhu Mythos skill has no skill check box; it never improves via the normal experience check system.
An investigator with Cthulhu Mythos 50 has a max Sanity of only 49. They can never be truly sane again.