METTLE Core vs Open Legend

Compare METTLE Core and Open Legend side by side. See differences in complexity, dice, genre, and more.

	METTLE Core	Open Legend
Genre	Universal, Modern	Universal
Tags	Pulp Action, Toolkit, Hackable, Rules-Light, Classless, Fast-Paced, CC-Licensed Rules	Toolkit, Classless, Hackable, Heroic, Modular, Character Building, Tactical, Crunchy
Core Mechanic	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.	Roll a d20 plus one or more attribute dice (d4 through d12 based on attribute score, scaling to multiple dice at higher scores) against a Challenge Rating. All dice explode on their maximum face and can keep exploding without limit. Characters have eighteen attributes split across Physical, Mental, Social, and Extraordinary categories; extraordinary attributes channel banes (negative effects) and boons (positive effects) instead of tracking a spell list. Advantage or disadvantage adds extra dice and drops the lowest or highest before summing.
Dice	d6 dice pool	d20 + d4–d12
Complexity	Low	Medium
Availability	Free core rules	Free core rules
Runnability	5 of 5 book tools	Book tools not listed
License	CC BY 4.0	Open Legend Community License (SRD)
Third-Party Publishing	Not yet researched	Not yet researched
Publisher	Planarian Games	Seventh Sphere Publishing
Year	2021	2018
Languages	English	English
Best For	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.	Groups who want a single classless engine to handle fantasy, science fiction, modern, or horror campaigns through eighteen attributes spanning physical, mental, social, and extraordinary domains, with magic and special effects folded into the same dice mechanic as combat.
Highlights	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.	All dice explode on maximum rolls with no cap, producing occasional dramatic result spikes through the same mechanic that handles ordinary rolls. Magic is folded into the attribute system through banes and boons, so extraordinary attributes like Energy or Entropy roll for fixed effects rather than tracking a spell list. Hits that exceed a defense by ten or more automatically apply a free bane on top of damage, so big roll-overs translate into status effects like knockdown or stunned rather than wasted overflow.
Considerations	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.	First-level character creation spends 40 attribute points across 18 attributes plus 6 feat points across a tiered feat list, producing heavy upfront decision load before play begins. Weapons have no damage dice (damage equals your action roll minus the target's defense), so weapon variety within a category is largely cosmetic, and the book itself notes that a longsword mechanically dominates a shortsword. Hit points come from Fortitude, Presence, and Will (HP = 2·(F+P+W) + 10) rather than from level, so a character who dumps all three stays near 10 HP regardless of how much XP they earn.