The Resolution Engine
Nearly every uncertain action uses one engine: roll d100 against an effective percentile value. Apply circumstances first, cap the effective value at 1–100, and compare the roll.
| Result | Requirement |
|---|---|
| Critical | Natural 01 |
| Extreme | At or below one-fifth, above 01 |
| Hard | At or below one-half, above Extreme |
| Regular | At or below the effective value, above Hard |
| Failure | Above the effective value |
| Fumble | 96–00 below effective 50; 100 at effective 50+ |
A fumble overrides apparent success and introduces a complication. In opposed checks, Critical beats Extreme, Extreme beats Hard, Hard beats Regular, and any success beats failure. Equal bands go to the lower roll; if both fail, the roll closer to its target wins.
Use modifiers for specific circumstances and bonus or penalty dice for broadly favorable or unfavorable situations. Do not stack several small bonuses merely to reward description. Preparation may instead remove a roll, reveal a clue, supply a tool, or improve the circumstances.
Luck is a player-facing safety valve: 1 point rerolls a failed action, adds +20% to one check, or automatically succeeds at a routine task without major risk. It refreshes after a full night's rest.
When designing a mechanic, identify its decision, its interaction with an existing value or skill, and its success, failure, and fumble outcomes. Prefer a modifier, opposed check, cost, or consequence over a new subsystem.