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Flexible dice

Free packv3.0.0-2Logic

A dice pool that leaves the rules to you. Standard dice, weighted dice, negative dice and symbolic attack and defence dice share one contract, any of them can be held, every roll can be replayed, and the exact odds of any result are a call away.

This is a Free pack. Every phaser.io account can use it in their games.

Released October 14, 2026 · updated October 19, 2026

Flexible dice: a screenshot of its demo
A note about these graphics

Expansion packs don't come with graphics. This screenshot is one way of drawing what the pack does, made for its demo: none of the sprites, tiles or backgrounds in it are in the pack.

That's by design. A pack is a game's logic, mechanics and effects, and it works with whatever art you give it. Some packs draw effects, backdrops or 3D scenes of their own, but none carries a game's sprites.

So the look is yours. Make the art on phaser.io, bring your own, or let your agent draw it in code: the same pack can look like anything.

What it does

createDicePool takes a seed and a list of dice. A die is a list of faces, each with a number or a string as its value, an optional label, and a weight that defaults to 1. standardDie builds the familiar fair ones, a d6, a d20 or a d100, and a pool can mix any of them. roll rolls every unheld die, or a chosen few, and hold keeps a rolled die's face for the next roll; release clears every hold at the end of a turn. Each roll returns an ordered event with every face that changed, ready to animate.

Rolls draw from the engine's seeded random stream, held inside the pool. snapshot saves the dice, the faces showing, the holds and the stream's state; restore checks the save against the pool before changing anything, and the next roll is the same as it would have been. Commands passed through apply can be recorded and replayed from a fresh pool with the original options, so a game can restart or show an animated replay without inventing outcomes. A selection that is refused, a held die or a duplicate, consumes no randomness.

diceProbability enumerates every outcome of a set of dice, with their weights, and returns the chance that your test is true: three sixes, at least two hits, a sum over 15. diceSumDistribution gives the chance of every total. Both answer only after the whole calculation fits within a budget, and otherwise say the budget ran out rather than guess.

Features

  • Any face — numbers, including negatives, or symbols such as attack and defend, with display labels.
  • Weighted faces — any positive weight, for loaded or uneven dice.
  • Mixed pools — up to 64 dice of up to 256 faces each, of any sizes together.
  • Holds — keep chosen dice and roll the rest, as in a five-dice scoring game.
  • Reproducible rolls — seeded, with saves that restore the exact next roll.
  • Replayable commands — roll, hold and release as data, for recording, replay and persistence.
  • Exact probabilities — the chance of any predicate, and the full distribution of sums, within a budget.
  • Safe observations — observation shows the faces and holds without the random state, for hints and bots.

Good for

  • Five-dice scoring games — roll, hold and roll again, with the odds for an advice feature.
  • Tabletop RPG checks — a d20 with modifiers, a d100 table, or damage dice of mixed sizes.
  • Board games with custom dice — symbol dice for combat, movement or resources.
  • Push-your-luck dice games — roll, keep what you like and risk the rest, with the odds shown.
  • Probability tools — show the player their exact chance of success before they roll.
  • Bots and hints — fair advice from the visible faces, never from the future rolls.

Make it yours

There are no pack options; every pool is defined by its seed and dice. A classic game might be five plain d6 held and re-rolled up to three times, with the turn limit and scorecard written by the game. A fantasy battle might mix a d20 for damage with a symbolic effect die whose faces are three hits to one guard, and ask diceProbability for the chance of at least two hits before the player commits.

A quick look

A mixed pool of a d20 and a weighted symbol die, rolled, with the d20 held for the next roll:

const dice = game.diceCore.createDicePool({ seed: 29, dice: [
    game.diceCore.standardDie('damage', 20),
    { id: 'effect', faces: [
        { id: 'hit', value: 'attack', weight: 3 },
        { id: 'guard', value: 'defend', weight: 1 },
    ] },
] });
dice.apply({ kind: 'roll' });
dice.apply({ kind: 'hold', id: 'damage', held: true });
dice.roll(); // Rolls only unheld dice.

Works with

  • yahtzee — classic and triple five-dice scoring, matches and advice, built on this pool.
  • geometry-3d — polyhedral dice meshes, for showing the faces in 3D.

Good to know

  • There is no physics: a roll is a weighted random choice, and your game animates the dice however it likes.
  • Scoring, turns, reroll limits, hidden dice and exploding dice are not here; they belong to the game.
  • "Exact" means every outcome was counted; the arithmetic is ordinary floating point.
  • The generator is for games, not for cryptography or regulated gambling.
  • Probability budgets default to 100,000 operations and go up to a million.

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