Tutorial: Your First Multiplayer Scene

This tutorial describes the smallest useful scene of your own. Use the showcase prefabs as references while you build it; they expose the exact inspector relationships that text cannot show as clearly.

1. Create the global settings

Create Assets > Create > RedEngine > EngineSettings and keep the asset at Assets/Resources/EngineSettings.asset. Assign:

• a prefab containing NetworkRunner;
• the default game scene;
• the server scene, if it differs;
• the default server port, if your connection flow uses one.

Do not add Fusion's NetworkSceneManagerDefault to the runner prefab. GameInstance supplies RedEngine's scene manager.

2. Add a game mode

Create a prefab with:

• NetworkObject;
• your GameModeBase subclass;
• its player-controller and default-character prefab assignments.

Place one instance of that game mode prefab in the gameplay scene. The server looks for the scene's game mode when the world initializes; a separate WorldSettings component is not required.

using RedEngine.Core;

public sealed class ArenaGameMode : GameModeBase
{
    public override void Spawned()
    {
        base.Spawned();
        // Initialize authoritative match rules here.
    }
}

3. Prepare player prefabs

The game mode needs a player controller and a character. Any spawnable network actor needs a NetworkObject, and network behaviors should derive from RedEngine's actor/component types where the framework owns their lifecycle. Register these prefabs in Fusion's network project configuration.

For a first pass, duplicate the corresponding showcase prefabs and remove features you do not need. That gives you a known-good hierarchy before you customize movement, visuals, or abilities.

4. Add input

1. Create a Unity Input Actions asset.
2. Create Assets > Create > Red Engine > Input > Input Settings.
3. Map actions to Move, Look, Primary, Secondary, or Button0…Button31.
4. Create an InputContext and route channel/trigger pairs to component methods.
5. Add the appropriate RedEngine input component to the player controller.

Handlers are explicit:

using RedEngine.Core.Input;
using UnityEngine;

public sealed class HeroInput : MonoBehaviour
{
    [InputHandler]
    public void Move(Vector2 value) { }

    [InputHandler]
    public void Jump() { }
}

Use Started for the press edge, Triggered while held, Ongoing after the first held tick, and Completed/Canceled for release. RedEngine keeps a separate Input Actions instance for each local peer.

5. Make the scene runnable

Add the gameplay scene to the active Build Profile and assign it in EngineSettings. Confirm every spawnable prefab is registered with Fusion. Then enter Play Mode with one peer first.

Once one peer spawns correctly, enable Fusion Multi-Peer and try two. Verify both input paths before adding inventory, abilities, or weapons; a small working baseline makes later failures much easier to locate.

6. Add one feature at a time

A practical order is:

1. movement and camera;
2. one gameplay ability;
3. one replicated attribute such as Health;
4. one interactable pickup;
5. inventory and equipment;
6. player UI;
7. diagnostics and developer commands.

Before opening a complete system guide, pick a focused task from Recipes. Each recipe adds one feature and includes a multiplayer check.