Universal roll-under rule
At the centre of the game is one simple rule: when something uncertain matters, the player rolls 1d20 and tries to get equal to or under the relevant Attribute.
Roll 1d20 equal to or under the relevant Attribute.
A result equal to the Attribute succeeds. I wanted one procedure that could carry almost everything, because solo play gets clumsy fast when the rules keep changing their language from one subsystem to the next.
Use this for:
- Attribute tests
- Attacks
- Defence
- Saves
- Spellcasting
- Resisting magic
- Physical danger
- Mental danger
- Social pressure when a roll is required
Critical results
Criticals stay simple as well. A natural 1 is a critical success and a natural 20 is a critical failure. For attacks, that means a natural 1 hits especially well and a natural 20 fails with a complication, but it does not default to the hero humiliating themselves for no reason.
- Natural 1: critical success
- Natural 20: critical failure
For attacks:
- a natural 1 increases damage by one Damage Step or grants an equivalent benefit
- a natural 20 fails and introduces a complication
Advantage and Disadvantage
Advantage and Disadvantage work the same way throughout the game. I kept them because they are easy to read at the table and they let Tags and fictional positioning matter without turning every bonus into arithmetic.
- Advantage: roll 2d20 and keep the lower result
- Disadvantage: roll 2d20 and keep the higher result
- Advantage and Disadvantage cancel
- Multiple sources do not stack
Tags
Every hero begins with three Tags.
A relevant Tag grants Advantage when it meaningfully applies.
Tags never add flat numerical bonuses. I would rather let them sharpen the fiction than turn them into another stack of modifiers to remember.
Difficulty
Difficulty also stays compact on purpose. I do not want a giant ladder of target adjustments when most solo decisions only need a quick sense of whether things are favourable, normal, hard, or severe.
- Favourable: Advantage
- Standard: normal roll
- Difficult: reduce the effective Attribute by 2
- Severe: reduce the effective Attribute by 4
The effective Attribute cannot rise above 19 or fall below 1.
General tests
Use the Attribute that best matches the action. If two options feel plausible, choose the one that best reflects how the hero is actually approaching the problem.
- Strength for force, lifting, wrestling, and direct physical pressure
- Dexterity for speed, precision, stealth, and evasion
- Constitution for endurance, poison, strain, and surviving hardship
- Intelligence for planning, recall, craft, and arcane method
- Wisdom for awareness, instinct, fear, and reading danger
- Charisma for command, intimidation, presence, and identity
Defensive tests
When danger strikes the hero, the player rolls Defence instead of the enemy rolling an attack. That is one of the main structural choices behind OHE. I want the pressure to stay on the hero’s sheet and the hero’s decisions, not on hidden enemy math.
Common Defence Attributes:
- Strength to block or resist force
- Dexterity to evade
- Constitution to endure
- Wisdom to resist fear, domination, or mental pressure
- Charisma only when supernatural presence, identity, or possession clearly applies
Time and scenes
Play in short scenes. Each scene should contain:
- one immediate objective
- one obstacle or threat
- one meaningful decision
- one consequence
End the scene when the objective succeeds, fails, is abandoned, or changes enough to become a new scene.
That scene-based structure matters because it keeps solo play moving. The game works best when each scene is allowed to do one meaningful thing and then get out of the way.
HP
Heroes do not use Hit Dice.
I wanted survivability to be easy to read and easy to recover from, so HP is based on full Constitution rather than derived from a separate class die.
Starting HP:
| Class | Starting HP |
|---|---|
| Fighter | Constitution + 6 |
| Rogue | Constitution + 3 |
| Magic User | Constitution |
At levels 3, 5, 7, and 9, gain +2 maximum HP.
MP
Magic User starting MP: 7
Magic User MP progression:
- level 3: +1 maximum MP
- level 5: +1 maximum MP
- level 7: +1 maximum MP
- level 9: +1 maximum MP
Recovery
Recovery is generous enough to keep the hero active, but not so generous that damage becomes meaningless. A short rest should feel like catching your breath, not erasing the whole session.
Short rest
- takes about ten minutes
- may be taken once per scene when fiction allows
- recovers
1d6 HP
Class recovery bonus:
- Fighter:
+2 HP - Rogue:
+1 HP - Magic User: no class bonus
Long rest
A long rest restores:
- all HP
- all MP
- once-per-day abilities
- temporary conditions unless a rule says otherwise
HP-to-MP conversion
You may sacrifice 2 HP to recover 1 MP.
This can never reduce you below 1 HP.
I like this rule because it gives magic a real cost without making spellcasting collapse once the MP pool runs dry.
Defeat
At 0 HP, the hero is Defeated.
The current scene ends against the hero unless a Trait explicitly prevents it.
Defeat is meant to end momentum, not automatically end the story. In solo play especially, I want failure to push the fiction somewhere sharper instead of just slamming into a dead stop.
Choose the consequence that best fits the fiction:
- escape with a Scar
- capture
- loss of an important item
- failure of the immediate objective
- rescue at a cost
- separation from an ally or resource
- a new danger created by the defeat
The hero returns with 1 HP once the immediate consequence is resolved.
Death occurs only when:
- the player chooses it as the right conclusion
- or the hero is Defeated again before completing a long rest and the fiction clearly allows no alternative