Welcome to Mythras Imperative
You are about to play a d100 roleplaying game. When something important is on the line—sneaking past a sentry, bargaining for safe passage, swinging a sword—you roll percentile dice and try to score equal to or less than a skill. Low is good. High is bad. Your chance of success is a percentage you can see at a glance.
That is the whole engine. Everything else in these pages hangs on it.
What you need
- A full set of polyhedral dice: d4, d6, d8, d10, d12, d20, and d100 (two d10s, one read as tens).
- A character sheet with Characteristics, Attributes, Skills, and Passions filled in.
- Pencil, paper, and a readiness to react to what the dice say.
You will also meet a few less common dice calls: a d2 (any die, odds 1 / evens 2, or a coin), and a d3 (1d6: 1–2 = 1, 3–4 = 2, 5–6 = 3).
Rolling under
When the Games Master calls for a skill roll, roll 1d100 against the skill’s current value (after any difficulty modifiers):
| Result | What it means |
|---|---|
| Equal to or under your skill | Success |
| Over your skill | Failure |
| 01–05 | Always a Success, even if the skill is tiny |
| 96–00 | Always a Failure, even if the skill is over 100% |
| One-tenth of the skill (round up) or less | Critical Success |
| 99 or 00 (00 only if the skill exceeds 100%) | Fumble |
A Critical is exceptional—the clean lockpick, the perfect water-break, the strike that finds a join in the armour. A Fumble is a mess: tools break, footing goes, the shot goes wide in the worst possible way. The Games Master decides the flavour; the dice decide when it happens.
When you do not roll
Not every task is a roll. Riding at a gentle canter across open ground, carving a chair leg at your own pace, quietly picking a simple lock with time and tools—if you have the skill and nothing is urgent or dangerous, success is automatic. Save the dice for when outcomes are uncertain or the moment matters.
Rounding
Whenever the rules divide a number (Critical range is one-tenth of a skill, for instance), always round fractions up. One-tenth of 63% is 7, not 6.
Who this book is for
These chapters tell you how to play: how to build a character, how skills and Passions work, how luck tips a fight, how combat delivers Special Effects and wounds, how magic and superpowers spend their pools, and how you improve between stories. Detailed skill write-ups, spell lists, creature stats, and equipment tables live in the project reference; use this handbook to learn the procedures, then look up the particulars when you need them.
Turn to Making a Character when you are ready to sit down with a blank sheet. If your table already has characters, skip ahead to The Core Game and come back when someone dies or a new recruit appears.