Taikyoku Shogi Engine

A complete engine for Taikyoku Shogi (大局将棋, "ultimate chess"), the largest known variant of shogi.

• 36 x 36 board (1,296 squares)
• 804 pieces (402 per side)
• 209 piece types with distinct movement patterns
• 92 additional promoted forms

Rules Overview

Objective

Capture all of your opponent's royal pieces (King and Crown Prince). The game ends immediately when a player's last royal piece is captured. Unlike standard shogi, there is no check or checkmate — you may move your King into danger.

Turns

Black (先手) moves first. Players alternate moving exactly one piece per turn. Passing is not allowed. Captured pieces are permanently removed (no drops).

Movement

Pieces move orthogonally or diagonally. Most pieces have unique movement patterns combining:

See PIECES.md for the complete movement reference for every piece.

Promotion

The promotion zone is the 11 rows on the opponent's side of the board.

• A piece may promote when it moves into the promotion zone from outside, or when it captures an opponent's piece while inside the zone.
• A piece that entered the zone without promoting may only promote later by capturing inside the zone, or by leaving and re-entering.
• Promotion is optional, except for forward-only pieces (Pawn, Stone General, Iron General, Dog, Wood General, Incense Chariot, Ox Chariot, Fierce Tiger) which must promote upon reaching the farthest rank.
• Promotion is permanent — a piece cannot revert to its unpromoted form.

Range Capture Ranking

Range-capturing pieces (Great General, Vice General, etc.) can fly over and capture all pieces along a line, but only pieces of lower rank:

1. King, Crown Prince — cannot be range-captured
2. Great General
3. Vice General
4. Flying General, Angle General, Fierce Dragon, Flying Crocodile

Initial Setup

Each side's 402 pieces occupy 12 ranks. Black occupies the bottom of the board (rows 25-36); White mirrors from the top (rows 1-12). The King sits at the center of the back rank, flanked by the Crown Prince.

Getting Started

Requirements

• Python 3.9+
• Rust toolchain (for the fast Rust backend)
• maturin (pip install maturin)

Build and Run

# Clone the repository
git clone https://github.com/jh85/taikyokushogi.git
cd taikyokushogi

# Create a virtual environment and install dependencies
python3 -m venv .venv
source .venv/bin/activate
pip install maturin

# Build the Rust backend
maturin develop --release

# Run the web GUI
python3 web_gui.py 8080
# Then open http://localhost:8080 in your browser

Web GUI Features

• Human vs Random — play as Black or White against a random-move player
• Random vs Random — watch two random players with adjustable speed
• Click a piece to see legal moves highlighted on the board
• Score graph tracks material balance in real time
• Piece info panel shows movement details on hover

Other Modes

# USI protocol mode (for GUI software)
source .venv/bin/activate
python3 -m taikyoku_engine

# Quick demo (board info + move count)
python3 -m taikyoku_engine demo

# Random game in terminal
python3 -m taikyoku_engine random 200

Pure Python (no Rust)

If you cannot install Rust, the engine falls back to pure Python automatically. Everything works, just slower (~80x slower for search).

python3 web_gui.py 8080

Project Structure

taikyokushogi/
  src/                    # Rust engine (PyO3)
    lib.rs                #   Public API + Python bindings
    python.rs             #   PyO3 bindings (behind feature flag)
    types.rs              #   Core types, ray tables
    pieces.rs             #   301 piece types, Betza parser
    board.rs              #   Board representation
    movegen.rs            #   Legal move generation
    eval.rs               #   Static evaluation
    search.rs             #   Alpha-beta search
  taikyoku_engine/        # Python engine (fallback)
    pieces.py             #   Piece data
    board.py              #   Board class
    movegen.py            #   Move generation
    evaluation.py         #   Evaluation
    search.py             #   Search
    usi.py                #   USI protocol
  web_gui.py              # Browser-based game GUI
  PIECES.md               # Complete piece movement reference
  Cargo.toml              # Rust project config
  pyproject.toml          # Python/maturin build config

Performance

Using as a Rust Crate

Add to your Cargo.toml:

[dependencies]
taikyokushogi = "0.1"

use taikyokushogi::{Board, Color};

let mut board = Board::initial();
let moves = board.legal_moves();
println!("{} legal moves", moves.len());

board.apply(&moves[0]);
println!("Score: {}", board.material_score());
board.undo();

// Search
let result = board.search(2, 5000);
if let Some(mv) = result.best_move {
    println!("Best: {}, score: {}", mv, result.score);
}

// Piece info
let info = taikyokushogi::piece_info("LN").unwrap();
println!("{}: {} (area={}, igui={})", info.name, info.value, info.area_steps, info.has_igui);

References

• Taikyoku shogi — Wikipedia