Call of Cthulhu vs METTLE Core

Compare Call of Cthulhu and METTLE Core side by side. See differences in complexity, dice, genre, cost, and more.

	Call of Cthulhu	METTLE Core
Genre	Horror, Modern	Universal, Modern
Tags	Investigation, Fear & Stress Mechanics, Mystery, Deadly, Corruption, Skill-Based, Atmospheric, One-Shot Friendly, Character-Driven, Narrative	Pulp Action, Toolkit, Hackable, Rules-Light, Classless, Fast-Paced, CC-Licensed Rules
Core Mechanic	Roll d100 equal to or below a skill or characteristic. Hard and Extreme tests use half and one-fifth of that rating. Bonus and penalty dice select a better or worse tens digit. Eligible failed skill rolls can be pushed by taking further action, risking a harsher consequence.	Roll a pool of d6s equal to the Attribute being used. Dice showing 1, 2, or 3 are summed as the Score; dice showing 4, 5, or 6 are counted as Edge. The Check succeeds if Score meets or exceeds the Difficulty (Routine 1 to Nigh Impossible 15), and Edge measures how well it went. On a failure with Edge, the player may call for a Twist: accept a complication proposed by the rest of the table, then reroll the Edge dice for a second chance. Initiative passes from the acting character to the target of their Action, who becomes the next to act. Mettle (Motive + Nature) acts as a combined morale and damage track, and characters may Surge by spending Mettle for bonus dice on critical Checks.
Dice	d100	d6 dice pool
Complexity	Medium	Low
Accessibility	High	Very High
Runnability	Very High	Very High
License	Chaosium Fan Material Policy	CC BY 4.0
Third-Party Publishing	Commercial publishing allowed — Community content program	Not yet researched
Summary only, not legal advice. Check current terms before publishing.
Cost	$$	Free
Publisher	Chaosium	Planarian Games
Year	2014	2021
Languages	English, French, German, Italian, Japanese, Korean, Spanish, Polish, Portuguese, Russian, Swedish, Chinese	English
Best For	Groups who want clue-driven horror with ordinary investigators and lasting consequences. Suits focused mysteries and campaigns where survival matters more than defeating every threat.	Groups who want fast pulp action-adventure in the vein of Indiana Jones, James Bond, or Tales of the Gold Monkey, with a hackable toolkit they can bend toward detective stories, wild-west gunfights, post-apocalyptic survival, or grounded science fiction.
Highlights	Pushing a failed roll offers another chance at the goal with a more serious consequence if it fails. Learning Mythos lore reduces maximum Sanity, tying useful knowledge to lasting vulnerability. An Idea roll gets a stalled investigation moving again, with failure putting investigators into danger.	Score-and-Edge dice pool reads two outcomes from the same roll: whether the action succeeds (Score meets Difficulty) and how well it went (count of 4–6 dice). Player-invoked Twists let a failed roll be reframed as a messy success in exchange for a fictional complication chosen by the rest of the table. Six-attribute character sheet (Calling, Culture, Frame, Motive, Nature, Poise) replaces classes and skills with player-written Descriptors that justify which Attribute applies to a given task. Initiative passes from the acting character to the target of their Action, eliminating turn-tracking and tying combat order to who is acting on whom.
Considerations	A major wound can leave an investigator dying, making direct confrontation dangerous. Bouts of madness temporarily place investigator actions under Keeper control. Foot and vehicle chases track relative speed and movement actions, adding a separate procedure to pursuit scenes.	Toolkit framing means the book provides scaffolding (factions, NPC seeds, sample castaway adventure) rather than a fleshed-out setting: groups expecting a defined world will need to build or borrow one. Mettle does triple duty as morale, hit points, and a spendable resource for bonus dice, which can take a session to internalize. Twist resolution depends on the rest of the table proposing complications, which slows play if the group is hesitant to add fiction.