The dice language

Every number in a rule system is either a plain number or a formula in one small language: the dice a check rolls, a target, a track's maximum, a stat's modifier, an enemy's health by tier, an amount on a rule card. You rarely need to write one: the sentence editor, the composer and Hob write them for you. The Advanced tab shows them all when you want to.

It is deliberately small. It is not a programming language: no loops, no reaching outside the values it's handed, nothing that can misbehave. A formula that doesn't make sense is refused when you save, in a sentence saying what's wrong.

Every face is kept in the roll's record, so the dice tray can replay it and the roll chip can show it. All dice roll from a seed: the same roll, rolled again for the same turn, gives the same faces.

Arithmetic

+ - * / and brackets: floor((@str - 10) / 2)

Comparisons

> >= < <= == !=, giving 1 or 0: @hp < 5

Logic

and, or, not: @cond.blessed > 0 and @nerve >= 3

Choices

if … then … else …: if @level >= 5 then 2 else 1. Only the branch taken is worked out, so only its dice are rolled.

Functions

floor ceil round abs min max clamp: clamp(@edge + @cond.edge, -1, 1)

A check has a roll and a way of reading it. The reading turns the dice into the outcome bands' measure:

On top of any reading, a check can compare two named dice (Hope against Fear): which came up higher adds a word to the outcome and its own effects; equal dice can be a critical.

Fifth-edition advantage, with conditions and exhaustion

(if @edge + clamp(@cond.edge + (if @exhaustion >= 1 then -1 else 0), -1, 1) > 0 then 2d20kh1
 else if @edge + clamp(@cond.edge + (if @exhaustion >= 1 then -1 else 0), -1, 1) < 0 then 2d20kl1
 else d20) + @stat.mod + @cond.mod

Classic d20's ability check: any number of disadvantages and advantages count once either way.

Pushing yourself for an extra die

if @stat + @spend_push <= 0 then 2d6kl1 else (@stat + @spend_push)d6

Forged in the Dark: zero dots rolls two and keeps the lower; paying the “push” spend (2 Stress) adds a die.

Hope, Fear, and a d6 if you spend Hope

d12[Hope] + d12[Fear] + @stat + (if @spend_hope > 0 then d6 else 0)

Percentile with bonus and penalty dice

d100t(@edge)                       read: roll under, target @stat.mod * @difficulty

A hunger pool: some dice are dangerous

(@stat - @hunger)d10>=6 + (@hunger)d10[Hunger]>=6

Count successes across both groups; then a rule card reads @group.Hunger.ones to turn a failure with a 1 on a Hunger die into something worse.

Degrees of success by ten

roll:  d20 + @stat.mod
read:  total against @difficulty, steps 10, naturals 20 / 1 shift the degree

An opposed lie

opposed: { "deception": "10 + @opp.insight.mod" }

A lie told to someone present is rolled against their passive Insight instead of a difficulty.