Implement Multiplayer Workflow

Overview

This skill guides you through enabling and integrating multiplayer functionality for games on the Remix platform.

Prerequisites

• A game must be created on the Remix platform (you need a game ID).
• The REMIX_API_KEY environment variable must be set.
• The game must include the RemixSDK script tag:

  <script src="https://cdn.jsdelivr.net/npm/@remix-gg/sdk@latest/dist/index.min.js"></script>
  

Steps

1. Check for Existing Game ID

Read .remix-settings.json in the current directory. If it exists and contains a gameId, use that value.

Only if .remix-settings.json does not exist or has no gameId should you follow the upload-game workflow to create one.

2. Enable Multiplayer

Enable multiplayer for the game via REST:

POST https://api.remix.gg/v1/games/{gameId}
Authorization: Bearer $REMIX_API_KEY
Content-Type: application/json

{ "isMultiplayer": true }

3. Integrate Multiplayer in Game Code

const sdk = window.RemixSDK
await sdk.ready()

// Access all players in the session
const players = sdk.players // Array of player objects

// Listen for game state updates from other players
sdk.onGameStateUpdated((state) => {
  // Sync game state from other players
})

// Send game state to other players
sdk.multiplayer.actions.gameOver({ scores: playerScores })

Important: Use Multiplayer gameOver

For multiplayer games, use multiplayer.actions.gameOver -- NOT singlePlayer.actions.gameOver. Pass a scores object keyed by player ID:

sdk.multiplayer.actions.gameOver({
  scores: { [playerId]: score }
})

Keep Standard Hooks

Multiplayer games still need these callbacks:

sdk.onPlayAgain(() => {
  // Reset game state and restart
})

sdk.onToggleMute(({ isMuted }) => {
  // Mute or unmute all audio
})

Tips

• Use sdk.players to get the list of players and their IDs.
• onGameStateUpdated fires whenever another player sends state -- use it to keep all clients in sync.
• Do NOT mix singlePlayer.actions.gameOver and multiplayer.actions.gameOver in the same game. Use one or the other.