Add host normalization and ResolveServerKey to match equivalent endpoints (localhost/127.0.0.1, bracketed IPv6, etc.) so reconnects reuse existing server profiles. Harden profile storage: sanitize save-folder components, use Documents fallback via _dupenv_s when needed, log write/open failures, and fix Windows build issues from unsafe getenv usage. Make session launch resilient to missing or rotated exit saves by accepting Exitsave... names, refreshing to the newest exit save, and falling back to first-time flow from the main menu (instead of hard-failing). Update session launch to prefer resolved profile keys, touch/bind profiles appropriately, and improve related load error handling. Also add a simple Creation Kit quest script (CO_Vault109StartQuestScript) and update changelog/docs to document these changes.
Commonwealth Online
Commonwealth Online is an experimental research project exploring the possibility of adding basic multiplayer-style networking to Fallout 4.
The goal is not to create a full co-op campaign mod immediately. The first goal is much smaller:
Two Fallout 4 clients in a controlled test environment, with each player visible as a synced remote actor.
This project is currently in the research and prototype stage.
Project Goals
First Prototype
- Load a native Fallout 4 plugin through F4SE
- Connect to a local test server
- Send local player position data
- Receive remote player transform data
- Represent another connected player using a placeholder actor
- Restrict all testing to a custom test cell
Long-Term Ideas
- Basic LAN multiplayer test mode
- Remote player movement sync
- Basic animation state sync
- Basic chat or debug messages
- Host-controlled test cell
- Simple co-op combat arena
Non-Goals
This project is not currently trying to support:
- Full Fallout 4 campaign co-op
- Quest synchronization
- Settlement synchronization
- Full NPC/world state synchronization
- VATS synchronization
- Public server/MMO gameplay
- Compatibility with large modlists
Those systems are extremely complex and are outside the scope of the first prototype.
Repository Layout
docs/ Project documentation and research notes
plugin/ Native F4SE/CommonLibF4 plugin work
creation-kit/ Creation Kit plugin files, Papyrus scripts, and test cell notes
server/ External multiplayer test server
protocol/ Network packet design and sync documentation
tools/ Helper scripts and utilities
test-data/ Example packets and test data
screenshots/ Development screenshots
Requirements
This project is expected to require:
- Fallout 4 on PC
- Fallout 4 Script Extender, F4SE
- Fallout 4 Creation Kit
- Visual Studio 2022 or newer
- CMake or another supported C++ build system
- A CommonLibF4-based plugin template
- Git
- A clean Fallout 4 test profile
Recommended Development Setup
Use a separate Fallout 4 installation or a dedicated modding profile for testing.
Recommended setup:
Fallout 4
F4SE
Creation Kit
Mod Organizer 2 or Vortex
Visual Studio
Git
Use a clean test save and avoid testing with a full personal modlist.
Legal Notice
This repository does not include Fallout 4 game files, Bethesda assets, F4SE binaries, or any proprietary game code.
Users are responsible for owning Fallout 4 and installing required external tools themselves.
Status
Current status:
Research phase
Repository structure setup
Protocol planning
No playable multiplayer build yet
License
To be decided.