Mope.io reverse engineered

A simple mope.io client that injects into the websocket. (Most packets were completely reverse engineered, 64 packets as of now)

Overview

This project builds and injects a userscript into mope.io to intercept all WebSocket packets. A Python controller manages the browser session via SeleniumBase (UC mode), injects the userscript, and drains packet logs.

Installation

Prerequisites

• Python 3.8+
• Chromium/Chrome browser

Setup

1. Clone the repository:

git clone https://github.com/aasb13/mopeio
cd mopeio

2. Create a virtual environment:

python3 -m venv .venv
source .venv/bin/activate

3. Install dependencies:

pip install -r requirements.txt

Usage

Build the Userscript

python3 scripts/build_userscript.py

This compiles the source files from src/userscript/ into a fat userscript.js.

Launch the Controller

python3 run_controller.py

Command-Line Options

• --browser: Browser to use (chromium, chrome, edge) [default: chromium]
• --url: Target URL [default: https://mope.io/]
• --headless: Run browser in headless mode
• --browser-profile-dir: Persistent browser profile directory
• --no-browser-profile: Use temporary profile instead
• --skip-build: Skip userscript rebuild
• --script: Path to prebuilt userscript.js
• --packet-log-file: Write packet logs to JSONL file [default: packet_logs.jsonl]
• --no-packet-log-file: Disable file logging
• --packet-log-stdout: Pretty-print packet logs to stdout
• --packet-log-viewer: Start web-based packet viewer
• --no-open-packet-log-viewer: Start viewer server without opening browser
• --no-debug-log-viewer: Disable debug viewer
• --no-open-debug-log-viewer: Start debug viewer without opening browser

Project Structure

mopeio/
├── assets/                 # Deobfuscated game source files
│   └── deobf.js            # Primary reference for packet structure
├── controller/             # Python controller logic
│   ├── browser.py          # Browser configuration and driver creation
│   ├── inject.py           # Userscript injection
│   ├── browser_log_pump.py # Log collection from browser
│   ├── log_viewer.py       # Log viewer server setup
│   └── main.py             # Main entry point
├── scripts/
│   └── build_userscript.py # Userscript build script
├── src/userscript/         # Userscript source files
│   ├── core/               # Core packet handling
│   ├── event/              # Event system
│   ├── module/             # Modular features
│   ├── network/            # Packet parsers
│   ├── structures/         # Game data structures
│   ├── ui/                 # UI components
│   └── utils/              # Utility functions
├── viewer/                 # Web viewer HTML files
│   ├── index.html          # Packet viewer UI
│   └── debug.html          # Debug log viewer UI
├── userscript.js           # Built userscript (generated, excluded from git)
├── requirements.txt        # Python dependencies
└── run_controller.py       # Controller entry point

Packet File Naming

Packet parsers in src/userscript/network/ follow the pattern:

{ID}_{C/S}{PacketName}.js

• ID: Packet ID number
• C: Client-sent packet
• S: Server-sent packet
• PacketName: Descriptive packet name

Example: 5_CMovementPacket.js (ID 5, client-sent, movement data)

Dependencies

• seleniumbase>=4.40,<5
• python-socketio>=5.12,<6