Caro (Gomoku)

A multiplayer Gomoku (Five-in-a-Row) game with client-server architecture. Play in the browser or from the command line.

Built on Netty (server) and Phaser 3 (web client).

Features

• 15x15 board with standard Gomoku rules
• Player vs Player (PVP) — create or join rooms, play against others online
• Player vs AI (PVE) — three difficulty levels (Easy, Medium, Hard)
• Spectator mode — watch ongoing games in real-time
• Web client — professional 2D game UI with canvas board, stone animations, sound effects
• CLI client — terminal-based client for lightweight play
• WebSocket + TCP — dual protocol support

Prerequisites

• Java 8+ and Maven — for the server and CLI client
• Node.js 18+ — for the web client (development only)

Quick Start

1. Build the server

git clone https://github.com/tiennm99/caro.git
cd caro
mvn clean package -DskipTests

2. Start the server

java -jar landlords-server/target/landlords-server-1.4.0.jar -p 1024

The server starts two listeners:

• TCP on port 1024 (for CLI clients)
• WebSocket on port 1025 (for web clients and the built-in web UI)

3. Play in the browser (Web Client)

Option A: Built-in web UI

Open http://localhost:1025/ in your browser. The server serves a basic web UI directly.

Option B: Phaser web client (recommended)

cd web-client
npm install
npm run dev

Open http://localhost:5173 in your browser. This is the full-featured Phaser 3 game client with:

• Wood-textured board with gradient stones
• Stone placement animations and hover preview
• Move history panel and turn indicator
• Sound effects (Web Audio API)
• Lobby with room management

To play multiplayer, open two browser tabs.

4. Play from the terminal (CLI Client)

java -jar landlords-client/target/landlords-client-1.4.0.jar -h 127.0.0.1 -p 1024

Enter moves as row,col (e.g. 7,7 for the center of the board). Type exit or e to leave.

Game Rules

• Two players take turns placing black and white pieces on a 15x15 board
• Black moves first
• The first player to form an unbroken line of 5 pieces (horizontally, vertically, or diagonally) wins
• The game ends in a draw if all 225 positions are filled

Project Structure

caro/
  landlords-common/    Java shared library (game logic, entities, protocol)
  landlords-server/    Java Netty server (TCP + WebSocket)
  landlords-client/    Java CLI client
  web-client/          Phaser 3 web client (Vite + vanilla JS)

Server Architecture

Client (browser/CLI)
  |
  +-- TCP  :1024  -->  ProtobufTransferHandler  -->  ServerEventListener_*
  +-- WS   :1025  -->  WebsocketTransferHandler -->  ServerEventListener_*
  +-- HTTP :1025  -->  StaticFileHandler         -->  static files

Web Client Architecture

web-client/src/
  main.js                    Phaser game boot
  config/
    game-config.js           Phaser config (800x800, Scale.FIT)
    protocol-constants.js    Server/client event code enums
  scenes/
    boot-scene.js            Connect to server
    menu-scene.js            DOM overlay menus
    game-scene.js            Board rendering + game interaction
  services/
    event-bus.js             Pub/sub event decoupling
    connection-service.js    WebSocket with heartbeat + reconnect
    game-state-service.js    Client-side state container
  objects/
    board.js                 15x15 grid with wood texture
    stone.js                 Gradient stones with drop animation
  ui/
    menu-ui.js               Nickname, lobby, room list, waiting room
    game-ui.js               HUD, move history, game over, toasts

Server Options

-p, -port    TCP port (default: 1024, WebSocket = TCP + 1)

CLI Client Options

-h, -host       Server address (required)
-p, -port       Server TCP port (default: 1024)
-ptl, -protocol Protocol: "pb" (TCP/Protobuf) or "ws" (WebSocket)
-lang           Language: "en" / "en_US"

Web Client Scripts

cd web-client
npm run dev      # Start Vite dev server (port 5173)
npm run build    # Production build to web-client/dist/
npm run preview  # Preview production build

Protocol

Communication uses JSON messages over WebSocket or Protobuf over TCP.

WebSocket message format:

{"code": "CODE_GAME_MOVE", "data": "{\"row\":7,\"col\":7}", "info": ""}

WebSocket endpoint: ws://host:{tcp_port + 1}/ratel

Credits

This project is based on Ratel by ainilili, originally a Chinese Landlords (Dou Di Zhu) card game. It has been converted to Gomoku (Five-in-a-Row) with a new web client.

• Original project: ainilili/ratel — Netty-based multiplayer game framework
• Networking: Netty — asynchronous event-driven network framework
• Web game engine: Phaser 3 — HTML5 game framework
• Build tool: Vite — next-generation frontend tooling

License

Licensed under the Apache License 2.0.