Game Creator 2 Networking Layer

Transport-agnostic, server-authoritative multiplayer support for Game Creator 2.

Online documentation · Releases

Release status: Alpha
The package is in alpha and its APIs, behavior, and documentation may change. The new Photon Fusion integration is specifically an early alpha feature.

What This Package Is

• A runtime networking layer for GC2 that is not bound to one networking SDK.
• A server-authoritative security model for cooperative and competitive multiplayer.
• A shared module contract that keeps GC2 gameplay integration consistent across transports.
• Setup, validation, migration, patching, demo, lobby, and GC2 Inspector visual-scripting tooling.

Supported Transports

Transport	Status	Included workflows
PurrNet	Alpha	Host/client transport bridge, LAN discovery and direct join, staging/ready-room lobby with chat, and an optional Steamworks.NET lobby/invite demo
Photon Fusion 2	Early alpha	Host/Client and Shared topologies, Photon matchmaking/lobby discovery, session bootstrap and diagnostics, character selection, chat, and Steam authentication/invite extension points

The Fusion integration uses Fusion/Photon connectivity. It does not replace Fusion's transport with Steam Datagram Relay. In Host/Client mode Fusion can use direct UDP or Photon Relay; Shared Mode uses Photon Relay.

Version 2.2.1 was validated against PurrNet 1.21.0 and Photon Fusion 2.1.1. The optional Advanced KCC driver was validated with Photon Advanced KCC 2.1.0. The complete public source snapshot contains both transport integrations, so install the corresponding SDK assemblies before importing or compiling their transport folders.

Optional Fusion Advanced KCC Driver

The optional Game Creator 2 movement driver for Photon Fusion Advanced KCC, introduced in version 2.1.0, remains available in version 2.2.1. Fusion Native remains the built-in, recommended default. Choose Advanced KCC when your project specifically wants its collision, prediction, resimulation, and render-presentation workflow.

• Photon Advanced KCC is a separate dependency and is not redistributed by this repository.
• The Fusion Scene Setup Wizard detects a compatible KCC API, manages ARAWN_GC2_FUSION_KCC, configures the nested KCC motor and GC2 driver, and validates authority and Fusion weaving setup.
• The optional adapter source is stored at OptionalIntegrations~/NetworkingLayerForGC2.FusionAdvancedKCC so Unity ignores it in this repository's flattened source layout.
• In a Unity project, install that folder as Assets/Arawn/NetworkingLayerForGC2.FusionAdvancedKCC, beside Assets/Arawn/NetworkingLayerForGC2. Keep the companion folder's .meta file and do not add an assembly definition to it.
• After installing Photon Advanced KCC, the optional movement-course demo can be installed from Game Creator > Install... as Advanced KCC Examples.

Network Actions and Replicated Object State

Version 2.2.0 adds transport-neutral Network Actions for authority-validated gameplay requests, confirmed transient events, and persistent replicated object state.

Version 2.2.1 fixes the Fusion client-readiness race that could reject a Network Action before initial snapshot acknowledgement, adds immediate local transport-failure responses and visible door-demo request results, and renders endpoint Conditions and Instructions through GC2's native UI Toolkit list tools.

• NetworkActionDefinition assets provide the trusted payload, authority, recipient, validation, reliability, and persistence contract.
• NetworkActionEndpoint components allow-list actions on admitted Fusion or PurrNet objects and bind authority checks plus local GC2 apply and snapshot Instructions.
• Persistent Boolean, Number, String, and Vector3 values are revisioned, broadcast through the selected transport, and reconstructed for late joiners and clients entering relevance.
• GC2 Instructions, Conditions, Events, and Properties cover requests, results, object-state reads, interaction context, and local state application for transforms, active objects, renderers, behaviours, colliders, layers, tags, visual variants, Animator parameters/states, and character controllability presentation.
• The Fusion and PurrNet Core Examples installers include an authority-validated replicated door-state example.

Network Actions replicate a trusted semantic value; they do not serialize or remotely execute arbitrary GC2 Instruction Lists. Authority commits the value once, then each receiving replica applies its locally authored presentation. Use absolute, idempotent snapshot Instructions for persistent state.

Supported Modules

• Core, Variables, Animation, and Motion
• Inventory
• Stats
• Shooter
• Melee
• Quests
• Dialogue
• Traversal
• Abilities (DaimahouGames third-party module integration)

Both transport integrations include bridges for the shared core and supported optional modules. The Fusion integration also includes GC2 Inspector Instructions, Conditions, Events, and Properties for session control and transport state.

Setup Wizards

• PurrNet: Game Creator > Networking Layer > PurrNet Scene Setup Wizard
• Fusion: Game Creator > Networking Layer > Fusion Scene Setup Wizard

The wizards create or reuse the transport session objects, shared GC2 managers, transport bridges, selected module bridges, player-prefab components, session profiles, registration assets, and optional demo UI. Use each wizard's Review and validation pages before applying changes to an existing scene.

Install examples through Game Creator > Install.... The former aggregate Fusion and PurrNet demo .unitypackage files were retired in version 2.2.0; the per-feature installers are the supported source of demo content and preserve explicit dependencies and upgrade versions.

Lobby Workflows

• The transport-neutral lobby API and canvas UI provide a common front end for hosting, discovery, joining, compatibility checks, and session capacity.
• PurrNet includes LAN discovery/direct-address joining plus an authoritative staging room with player list, ready states, configurable launch policies, capacity enforcement, join-in-progress rules, and chat.
• Fusion includes Photon session discovery and joining through its lobby/matchmaking service.
• The optional PurrNet Steamworks.NET demo adds Steam lobbies and invites and remains compile-safe when Steamworks.NET is absent.
• Fusion exposes region, authentication, visibility, capacity, session-property, and force-Photon-Relay start options. Steam authentication and invite metadata can be supplied by project-level adapters without coupling the core integration to a Steamworks wrapper.

Patch System

Use Game Creator > Networking Layer > Patches outside Play Mode. Each transport wizard validates the required patch for every selected module.

• Inventory, Melee, Shooter, and Traversal networking require their current server-authority patches.
• Shooter also requires the remote-camera-safety Sight patch.
• Updating or reinstalling a patched GC2 module can overwrite its hooks. Rerun Patch Status and reapply anything reported missing or stale.
• The Networking Layer fails closed when required hooks are unavailable.

Compatibility

Servers and clients must use the same Networking Layer version. Version 2.2.1 contains the Network Actions and Core interaction wire contracts introduced in 2.2.0 and must not be mixed with older builds. Every peer in an Advanced KCC session must also use the compatible optional adapter and Photon addon version.

Documentation

• General quickstart
• PurrNet overview
• Fusion overview
• Fusion Advanced KCC companion guide

Contributing

The recommended flow is fork, branch, and pull request.

1. Fork the repository and create a branch from main.
2. Keep changes scoped and atomic.
3. Verify Unity compiles cleanly for every affected module.
4. Open a pull request describing what changed, why, and how to test it.

Preserve Unity .meta files and GUIDs. The repository root is a flattened mirror of Assets/Arawn/NetworkingLayerForGC2/, plus the repository README, license, and optional integrations stored below OptionalIntegrations~.

License

This networking layer is MIT licensed. See LICENSE.md.