Play your way
Host your open world through Steam Networking, join friends, or connect to a dedicated server by IP or Steam ID.
Community multiplayer for Space Engineers 2
Your world.
Your crew.
Build together.
Bring friends into your next build. Host a session, join a persistent server, and make a corner of space your own.
v0.13.0 / Windows x64 / SE2 2.4.0.95
Y51 / SE2 ONLINE
Room for your next crew.
Room for your next crew.More room to build
Space is better
with company.
SE2 Online is a community multiplayer plugin for Space Engineers 2. Multiplayer lives in the game's menus, with no separate launcher or plugin license key.
An experimental community project by yellow51. It is not an official Keen Software House multiplayer release.
Your builds. Your faction.
Claim grids, choose private, faction or everyone access, and manage your faction from the in-game UI.
Keep a world going
Run a headless Windows dedicated server with saved worlds, configurable settings, console commands and a save before graceful shutdown.
Join the crew
Get SE2 Online.
Ready to play or ready to build?
Choose the release that suits you.
Steam account required
Sign in. Verify your game. Download.
Compiled releases and source are available to verified Space Engineers 2 owners. Your Steam password stays with Steam.
Make Game Details public in Steam privacy settings so Steam can verify your game. Private libraries cannot unlock downloads. Family access alone does not establish ownership.
For players
ZIPCompiled plugin
The ready-to-play client plugin. Extract it, set your Steam launch options, and open Multiplayer in game.
For builders
ZIPSource code
Compile the plugin and dedicated runner yourself. Includes the solution, source, tests, build scripts and example configuration.
For server hosts
ZIPDedicated server
A headless Windows x64 server with a live console. Requires the SE2 2.4.0.95 game files on the server.
For server hosts
ZIPStandalone server
The dedicated server bundled with the SE2 2.4.0.95 runtime files and portable .NET, so the server PC needs no game install. Extract to a short path such as C:\SE2Server with 7-Zip; Windows Explorer can skip long paths.
The source archive contains the plugin and dedicated runner source, build scripts and example configuration. Compiling requires your own compatible SE2 installation. The dedicated server download uses an installed copy of SE2 on the server PC. The standalone server bundles the SE2 runtime files instead, so the server PC needs no game install.
From download to your world
Ready for takeoff.
Start with a compatible game build.
Keep your plugin and host versions in sync.
- 01
Extract the plugin
Download the compiled plugin and extract it into a folder without spaces, such as
C:\SE2Online. Keep the included Content folder beside the DLL. - 02
Set your launch options
In Steam, open Space Engineers 2 → Properties → Launch Options, then add:
-allowMultiple -plugins:C:\SE2Online\Y51_SE2Online.dllUsing Pulsar, the SE2 plugin loader? Skip the launch options and add
Y51_SE2Online.dllto Pulsar as a local plugin instead. - 03
Meet in game
Launch through Steam. Open Multiplayer in the main or pause menu to host a world, browse servers and sessions, or use direct connect.
Prefer to compile it yourself?
Install the .NET 9 SDK and SE2 2.4.0.95, extract the source, and run this from its root in PowerShell. Replace the game folder with your own installation:
dotnet build Y51_SE2Online/Y51_SE2Online.sln -c Release /p:SE2Bin="C:\SteamLibrary\steamapps\common\SpaceEngineers2\Game2"The archive's SOURCE-README.md includes packaging and dedicated server build commands.