A simple Godot addon that streamlines multiplayer

Features

• Peer-to-peer multiplayer without dedicated servers or port-forwarding
• Works with Godot's high-level multiplayer API
• Uses relay servers to route game data between peers
• Perfect for indie games that don't want to manage dedicated servers

Prerequisites

• Godot 4.3 or newer.
• NodeTunnel is still in beta, you may encounter some issues.
• Relay servers are a bulletproof way to connect behind NAT, but latency will always be higher than direct connection, and likely higher than a dedicated server.
• NodeTunnel is built for session-based games (games like Lethal Company, Phasmophobia, etc.)

Installation

1. Install NodeTunnel in the asset store: https://store.godotengine.org/asset/androodev/nodetunnel/ (in Godot 4.7 or higher). Or download the latest release of NodeTunnel under releases
2. Download nodetunnel.zip if on Windows or Mac, Linux users should download nodetunnel.tar.gz
3. Decompress the downloaded file and drag n' drop the nodetunnel folder into res://addons in Godot
4. Make sure the NodeTunnel plugin is enabled in project settings

Using NodeTunnel

NodeTunnel's API is very easy to use. Because NodeTunnel integrates with Godot's high-level multiplayer API, converting your ENetMultiplayerPeer setup is super simple. All of your game logic will work identically with NodeTunnel, and the only thing that needs changed is making connections. Here's a basic run-down of how it works.

Connecting to Relay Server

Before hosting or joining a room, you must first connect and authenticate with a relay server. You can do this in a _ready function in a script where you handle multiplayer setup. Here's an example:

# multiplayer_example.gd

var peer: NodeTunnelPeer

func _ready() -> void:
	peer = NodeTunnelPeer.new()
	peer.connect_to_relay("us-east.nodetunnel.io:8080", "my_random_app_id")
	multiplayer.multiplayer_peer = peer
	
	print("Authenticating")
	await peer.authenticated
	print("Authenticated!")

Note: You can use whatever app ID you want, but make sure it's somewhat unique. Conflicting app IDs will result in issues. This is obviously an issue and will be fixed soon.

Tip

Hosting the relay server at us-east.nodetunnel.io has costs. I am happy to do it for free, but please consider a one time or recurring membership to GitHub Sponsors (jonandrewdavis) or AndrooDev Patreon to support it and NodeTunnel development. Thanks!

Hosting a Room

After authenticating with the relay server, you may then host a room. Doing so is easy:

# multiplayer_example.gd

var peer: NodeTunnelPeer

func host_room() -> void:
	peer.host_room(true, "My Room", 4)
	
	print("Hosting room...")
	var room_id = await peer.room_connected
	print("Connected to room: ", room_id)

After creating a room, the room_connected signal will eventually emit after the relay server has processed the request. It returns a room ID, which can be shared to allow other players to join.

Joining a Room

After authenticating with the relay server, you may then join a room after receiving a room ID.

# multiplayer_example.gd

var peer: NodeTunnelPeer
# Get this from a LineEdit or something
var room_id: String

func join_room() -> void:
	peer.join_room(room_id)

  print("Joining room...")
  var connected_room_id = await peer.room_connected
  print("Connected to room: ", connected_room_id)

Notice that NodeTunnelPeer.room_connected runs on both hosting and joining clients.

Handling Errors

Whenever the relay server encounters an error with a function the client called, it will emit the error signal. It is highly recommended that you implement some sort of error handling. Here's a basic example that prints out any errors:

# multiplayer_example.gd

var peer: NodeTunnelPeer

func _ready() -> void:
	peer = NodeTunnelPeer.new()
	
	peer.error.connect(
		func(error_msg):
			push_error("NodeTunnel Error: ", error_msg)
	)
	
	peer.connect_to_relay("us-east.nodetunnel.io:8080", "test_123213213")
  ...

Notice that the error signal is connected before calling any other functions. connect_to_relay can result in an error.

What Next?

After joining or hosting a room, everything remains the same as ENetMultiplayerPeer. Use multiplayer.peer_connected signals, MultiplayerSynchronizers, Spawners, etc.!

Hosting your own Nodetunnel relay server

Hosting can be done on any platform by running the Rust project or using the Docker image. See server source: https://github.com/NodeTunnel/relay-server.

License

MIT. See LICENSE.