@fortemate/dicechess-engine 🎲♟️

High-performance, cross-platform game engine and move generator for Dice Chess, compiled to pure Javascript (ES Modules) with full TypeScript type declarations.

Designed for maximum performance in web browsers, hybrid apps, and Node.js servers.

Installation

Install the package from npmjs.org via npm or your preferred package manager. No registry mapping or authentication token is required:

npm install @fortemate/dicechess-engine

An authenticated mirror is also available from GitHub Packages.

Two entries: the whole engine, or the rules alone

The package has two entry points. They come from one build and share the code they have in common, so importing both in the same application loads the shared half once.

| Import | What it gives you | What it loads | | :--- | :--- | :--- | | @fortemate/dicechess-engine | everything: DiceChess, EngineFacade, the legal turn tree, the bots, getBestMove, equity, doubling and draw decisions | 1,308,539 B (191,262 B gzipped) | | @fortemate/dicechess-engine/rules | the rules only: getLegalUciMoves, generateMoves, applyMove, endTurn, perft, getPieceFromDice, canonicalKey | 891,712 B (138,394 B gzipped) |

Use /rules wherever the application validates, applies and renders moves but never asks the engine to play — a live game against another human, a board editor, an analysis view. The functions are identical in name and behaviour to their DiceChess counterparts, so migrating is one import:

import { DiceChess } from '@fortemate/dicechess-engine/rules';

const dfen = "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1 PN";
const legalMoves = DiceChess.getLegalUciMoves(dfen);
const nextDfen = DiceChess.applyMove(dfen, "e2", "e4");

Both entries also export their functions as plain named exports (import { getLegalUciMoves } from '@fortemate/dicechess-engine/rules'), and each has its own TypeScript declarations (dicechess-rules.d.ts for the subpath).

The WebAssembly package @fortemate/dicechess-engine-wasm has no /rules subpath: the Scala.js WebAssembly backend emits a single module, so that package ships the full API only.

Quick Start (JavaScript / TypeScript)

The package is distributed as a standard ES Module (type: "module").

import { DiceChess } from '@fortemate/dicechess-engine';

// Dice Chess FEN (DFEN) encodes the board state and the current dice pool as the 7th field
// (e.g. "PN" represents a rolled Pawn (P) and Knight (N))
const dfen = "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1 PN";

// 1. Get all legal moves as a flat array of UCI strings for the DFEN position
const legalMoves = DiceChess.getLegalUciMoves(dfen);

console.log("Legal moves in this turn:", legalMoves);
// e.g. ["e2e3", "e2e4", "b1c3", "b1a3", ...]

// 2. Get every legal turn as a prefix tree of UCI micro-moves. A node without children is a
// complete turn. getLegalUciMoves judges each position in isolation, so a client that follows
// a turn one action at a time walks this tree instead of calling getLegalUciMoves again.
const turns = DiceChess.getLegalTurnTree(dfen);
console.log("Continuations of e2e4:", Object.keys(turns["e2e4"]));
// e.g. ["b1a3", "b1c3", "g1e2", "g1f3", "g1h3"]

// The dice a legal turn can still spend: pass the rolled DFEN and the moves played since, not the
// DFEN after them, because the turn is judged as a whole. A client can dim every other die.
console.log("Playable after e2e4:", DiceChess.getPlayableDice(dfen, ["e2e4"]));
// "N"

// 3. Apply a micro-move. applyMove preserves the active color (White), since a Dice Chess turn
// may consist of multiple micro-moves, and keeps the dice the move did not spend ("N" here).
// Arguments: (dfen, fromSquare, toSquare, optionalPromotionPiece)
const nextDfen = DiceChess.applyMove(dfen, "e2", "e4");
console.log("DFEN after micro-move:", nextDfen);

// Spend the knight die too: the turn ends at a leaf of the tree, here after e2e4 then g1f3.
const turnDfen = DiceChess.applyMove(nextDfen, "g1", "f3");

// 4. Explicitly end the turn when the player has exhausted their dice.
// This toggles the active color to Black, clears the dice pool (the full-move number advances
// only after Black's turn), and clears any stale en-passant targets from the previous turn.
const finalDfen = DiceChess.endTurn(turnDfen);
console.log("DFEN after ending turn:", finalDfen);

// 5. Discover available bots (search algorithms)
const bots = DiceChess.getAvailableBots();
console.log("Available bots:", bots);
// e.g. [ { id: 'random', name: 'Random', description: '...', difficulty: 1, isExperimental: false }, ... ]

// 6. Discover the built-in time-management policies.
const timePolicies = DiceChess.getAvailableTimePolicies();
console.log("Available time policies:", timePolicies);
// [ "empirical-v1", "legacy-linear-v1" ]

// 7. Compute the best sequence of micro-moves using the greedy bot search.
// The bot needs Black's roll: append the dice (lowercase for Black), here a Pawn and a Knight.
// Arguments: (dfen, optionalOptions)
const rolledDfen = `${finalDfen} pn`;
const botResult = DiceChess.getBestMove(rolledDfen, { algorithm: "greedy" });
console.log("Bot moves:", botResult.moves);
// e.g. [ { from: "b8", to: "c6" }, { from: "a7", to: "a5" } ]

// Clock-aware searches use empirical-v1 by default. Pass legacy-linear-v1 to
// reproduce the original allocation for rollback or an A/B comparison.
const timedResult = DiceChess.getBestMove(rolledDfen, {
  algorithm: "monte-carlo",
  clock: { remainingMs: 180_000, incrementMs: 2_000, moveNumber: 8 },
  timePolicy: "empirical-v1",
});
console.log("Effective budget (ms):", timedResult.budgetMs);

// 8. Doubling Cube & Draw Offers (New)
// Check if the bot wants to offer a double before its turn:
const shouldDouble = DiceChess.shouldBotOfferDouble(finalDfen, 1);

// Check if the bot accepts a double proposed by the opponent (Take/Drop):
const acceptDouble = DiceChess.shouldBotAcceptDouble(finalDfen, 2);

// Check if the bot wants to offer a draw:
const offerDraw = DiceChess.shouldBotOfferDraw(finalDfen);

// Check if the bot accepts a draw proposed by the opponent:
const acceptDraw = DiceChess.shouldBotAcceptDraw(finalDfen);

Features

• Complete Dice Chess Rules: Implements turn sequencing, unblocking, promotion path calculations, and strict Maximal Micro-moves Filtering.
• Type-Safe: Shipped with hand-written TypeScript definition files (.d.ts) for both entries, kept in step with the exported Scala.js API.
• Side-Effect Free: Configured with sideEffects: false to allow advanced tree-shaking in modern bundlers like Vite, Webpack, and Rollup.
• Blazing Fast: Optimized bitwise operations compiled via the advanced Scala.js optimizing linker.

API Reference & Documentation

• Interactive User & Developer Guide: Complete rules, architectural documentation, and live interactive visual catalogs.
• GitHub Repository: Source code, issue tracker, and contribution guidelines.

License

This package is licensed under the GNU Affero General Public License v3.0 only (SPDX AGPL-3.0-only).