Vibe Coding with Watchtower

Building multiplayer games with AI assistance? This page is for you.

Whether you're using Cursor, Claude, Copilot, or any other AI coding assistant, Watchtower's simple API makes it easy to add multiplayer to any project. One import, one function call, done.

Quick Reference Download

Download our single-page markdown reference to include in your AI context:

Download watchtower-quickref.md

Add this file to your project root, @docs folder, or paste it directly into your AI context.

The Essentials

Here's what you need to know:

1. Install

npm install @watchtower-sdk/core

2. Connect

import { connect } from '@watchtower-sdk/core'

const room = await connect('room-name')

3. Send Messages

// To everyone
room.broadcast({ x: 100, y: 200 })

// To one player
room.send('player123', { private: 'message' })

4. Receive Messages

room.on('message', (from, data, meta) => {
  // Handle incoming data
})

5. Track Players

room.on('join', (player) => { /* new player */ })
room.on('leave', (player) => { /* player left */ })

room.players     // current player list
room.isHost      // am I the host?

Common Patterns

Cursor Sharing

document.onmousemove = (e) => {
  room.broadcast({ x: e.clientX, y: e.clientY })
}

room.on('message', (from, pos) => {
  cursors[from] = pos
})

Turn-Based

// Host manages turn order
if (room.isHost && currentTurn === room.playerId) {
  room.broadcast({ type: 'move', data: moveData })
}

Host Authority

// Only host processes game state
room.on('message', (from, data) => {
  if (room.isHost) {
    const result = processAction(data)
    room.broadcast({ type: 'state', result })
  }
})

Debugging

Enable debug mode to see all WebSocket activity in the console:

const room = await connect('my-room', { debug: true })

// Console shows:
// [Watchtower] Connecting to my-room
// [Watchtower] Connected! playerId: p_abc123 isHost: true
// [Watchtower] ← join {...}
// [Watchtower] → broadcast {...}

Key Properties

Property	Description
`room.code`	Room code to share
`room.playerId`	Your player ID
`room.isHost`	Are you the host?
`room.players`	All players in room
`room.history`	Recent events
`room.connected`	WebSocket status

Tips for AI Sessions

Keep it simple — One connect(), broadcast what you need, done
Use debug mode — Add { debug: true } to see what's happening
Host authority — Use room.isHost for authoritative game logic
No persistence — Rooms are ephemeral; use your own storage if needed
Auto-reconnect — Built in, just works (unless kicked)

Need More?

Quick Start Guide — Step-by-step tutorial
SDK Reference — Complete API documentation
Game Patterns — Common implementation patterns