How to Play Fields of Mistria Multiplayer With a Mod

✦Understand what this multiplayer setup is

The Steam version of Fields of Mistria is still officially single-player. The Multiplayer Mod is a third-party project by D3Ulo that adds an experimental host-and-client workflow; it is not an NPC Studio feature, official server, or promise of future co-op support.

Keep the status question separate from the installation question. Use the official multiplayer status guide when deciding whether the base game includes co-op, and use this page only when you accept the maintenance and save risks of an unofficial Mod.

✿Check versions before changing the game

This guide was checked on 2026-08-16 against Fields of Mistria 1.0.3, MOMI 0.15.5, and the Mod page's latest listed changelog 4.1. Those numbers are a compatibility snapshot, not a guarantee that a later patch will work without an update.

Compare the game build, MOMI release, Multiplayer Mod file, relay release, and every required dependency on all computers. Stop before loading an important save if one player has a different build or the author has not confirmed the current game patch.

◆Back up saves and prepare both sides

Copy every participating save to a location outside the game and Mod folders before installing anything. Keep one untouched pre-multiplayer copy, then use a separate test save for the first connection, disconnect, reload, and recovery checks.

Ask every player to use the same game patch, MOMI version, Multiplayer Mod version, and required dependencies. Decide which computer will host the world and which character save each joining player will load. Do not make the only copy of a long-running farm the first test.

• Create an untouched backup outside the game directory.
• Use a disposable or copied save for the first session.
• Match the game, MOMI, Multiplayer Mod, relay, and dependency versions.
• Choose the host world before anyone connects.

★Install MOMI and the Multiplayer Mod

Download MOMI from its GitHub releases and the Multiplayer Mod from D3Ulo's Nexus page. Follow each project's current README and file instructions rather than a re-upload or old video. Place the Mod package in the location MOMI expects, preserving the folder structure so its manifest is not hidden inside an extra nested directory.

Run MOMI, confirm the Multiplayer Mod appears in the list, select it, and install. If it does not appear, recheck the archive extraction, manifest location, dependencies, and minimum MOMI version. After a game update, return to the original release pages and reinstall only after compatibility is confirmed.

▤Start the relay and host the world

The host runs the external relay supplied by the project, then opens the Mod's Multiplayer settings in the game and enters the connection details documented by the author. Use an address and port that are reachable only through a network path you understand; this guide does not recommend bypassing operating-system security controls.

Load the host's copied world only after the relay is ready. Confirm the game reaches a stable scene before inviting another player, then note the in-game date, location, and quest state so a synchronization problem can be reproduced without guessing.

◇Join with a separate character save

A joining player starts the same Mod version, enters the host address and port in the Multiplayer settings, and loads the character save intended for that session. The host supplies the shared world state while each participant still needs to protect the character save selected on that computer.

For the first session, test movement, an area change, a simple inventory action, saving, disconnecting, and reconnecting before doing story progression. If players see different objects, routes, or quest gates, stop and preserve both saves rather than forcing more progress into a desynchronized state.

✦Know the LAN and remote connection boundary

The author describes play on the same network or through a host connection that the joining computer can reach. A successful relay launch does not prove that the host address is reachable from another network, and two game instances on one computer do not create a native local co-op interface.

Network changes depend on the host's router, operating system, and security policy. Use the relay documentation and a network configuration you already administer. Do not install an unrelated tunneling tool or weaken security settings merely because an old guide uses it.

✿Expect incomplete synchronization and no split-screen

The author warns that some progression-gated world states are not synchronized. One documented example is the route to the summit: a newly created joining character may still need to complete the relevant events before those stairs unlock on that client.

The Mod does not turn Fields of Mistria into split-screen. Running two clients on one machine remains two separate game instances, not a shared-screen mode. Future game patches, engine changes, MOMI releases, or Mod updates can also invalidate a setup that worked previously.

◆Recover from a failed session or update

Stop the relay and close every game client before changing files. Preserve the affected saves, disable or uninstall the Multiplayer Mod through its documented workflow, restore clean game files if needed, and reproduce the issue with a copied save in an unmodified client.

If the clean client works, reinstall matching versions one dependency at a time. If the save itself remains damaged or inconsistent, restore the untouched pre-multiplayer backup instead of repeatedly overwriting it. Report the game patch, MOMI and Mod versions, host or join role, exact action, and visible difference to the relevant maintainer.