This is not intended to be a production MMO. It is a learning project focused on networking concepts, client/server communication, player synchronization, and game architecture.

Project Goals

Learn multiplayer game architecture
Experiment with real-time player movement synchronization
Build a lightweight backend using self-hosted tools
Learn how game clients communicate with servers
Explore Docker-based deployment
Create a foundation that could support small LAN multiplayer games

Current Technology Stack

Game Client

GDevelop

Used for:

Game logic
Scenes/rooms
Player movement
Object spawning
UI
Networking events

Real-Time Communication

MQTT (Mosquitto)

Used for:

Player join events
Player movement events
Player leave events
Room-based communication

Players communicate through MQTT topics based on their current room.

Database/API

JSON Server

Used for:

Player accounts
Persistent player information
Player location data
Player status

Current player data includes:

Username
Password
Player color
Current room
Last room
X/Y position
Online status

Current Multiplayer Design

Players are separated into rooms/scenes.

When a player enters a room:

The client updates its current room.
The client queries JSON Server for existing players in that room.
Existing players are spawned locally.
The player publishes a join message over MQTT.

Example join message:

{
  "type": "join",
  "player_id": 1,
  "x": 320,
  "y": 192,
  "color": "player_color"
}

Movement Synchronization

The current movement system uses MQTT messages to synchronize players.

Movement events include:

Move Start

Sent when a movement key is pressed.

Example:

{
  "type": "move_start",
  "player_id": 1,
  "angle": 0
}

Move Stop

Sent when the key is released.

Includes the player's final position:

{
  "type": "move_stop",
  "player_id": 1,
  "x": 450,
  "y": 200
}

This allows clients to predict movement locally while periodically correcting position.

Backend Services

A future goal is to package the backend into Docker containers.

Planned services:

MQTT broker
JSON Server
Python utility service

The Python service may eventually handle:

Server time
Day/night cycle management
Player timeout detection
Offline status cleanup
Server-side events

Project Structure

Planned structure:

GameProject/
│
├── gdevelop/
│   ├── Game project files
│   └── Assets
│
├── docker/
│   ├── MQTT configuration
│   ├── JSON Server configuration
│   └── Utility services
│
├── database/
│   └── db.json
│
└── README.md

Current Status

Working:

Player registration
Player login
Room switching
MQTT communication
Player spawning
Multiple players visible in the same room
Basic player synchronization

In Progress:

Improved movement synchronization
Better player disconnect handling
Server-controlled time system
Additional game mechanics

Future Ideas

Possible future features:

Real-time day/night cycle
Calendar events
NPCs
Persistent world state
Inventory system
Chat system
Small LAN multiplayer deployment

Disclaimer

This project is primarily a learning exercise.

The current architecture is designed for experimentation and small-scale multiplayer use. It is not intended to be a secure public-facing MMO backend.

Security, authentication, and server authority would need significant improvements before public deployment.