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
Play Style	Investigation, Deadly, One-Shot Friendly, Atmospheric, Roleplay-Heavy, Mystery, Horror, Corruption, Skill-Based	Pulp Action, Cinematic, Toolkit, Hackable, Open Source, Rules-Light, Theater of the Mind, Narrative, Classless, Fast-Paced, Fiction-First, Random Tables, GM-Friendly
Core Mechanic	Roll d100 equal to or under your skill percentage. Success tiers at half (Hard) and one-fifth (Extreme) of the skill value. Bonus and penalty dice adjust the tens digit. Failed rolls can be pushed for a second attempt at greater risk.	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	Medium	Very High
Runnability	High	High
License	Chaosium Fan Material Policy	CC BY 4.0
Cost	$$	$
Publisher	Chaosium	Planarian Games
Year	2014	2021
Best For	Investigation-driven horror where combat is deadly and sanity is fragile. Great for one-shots.	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	Sanity system mechanically reinforces horror tone. Intuitive percentile skill system with tiered success levels. One of the largest published scenario libraries in the hobby.	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	Chase rules add complexity with limited payoff, 46-skill list requires point allocation across multiple categories, sanity spiral can remove player agency in extended campaigns	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.