Will it run on Linux?

Not as Keen ships it: the server is built for Windows. Community guides run it under Wine, but Keen publishes no Linux build or Linux instructions, so you are relying on those guides when an update breaks something. Windows Server is the dependable route.

What do I forward so people can join?

UDP 27016, or whichever listen port you set. That is the only port Keen asks you to open. Keep the remote admin port, 8080 unless changed, closed to the public.

How many players can it hold?

You choose the cap in the settings, and the -maxPlayers start-up option overrides it. Keen doesn't publish hardware figures per player, so start from its recommended machine and watch simulation speed in the Remote Client as your crew grows.

Do I need to buy the game again for the server?

No. Keen says the dedicated server needs no licensed copy of its own, though it adds that getting the files takes a Steam account licensed for the game. Its own SteamCMD example fetches app 298740 signed in as anonymous.

Who pays for Windows?

You do, as its own monthly line: a licence priced per core, flat up to eight cores. Paying the server several months ahead does not discount it.

Space Engineers Dedicated Server for Your Crew

First, know it's a Windows server

Keen's own guide begins with a Windows PC, and the program you run is SpaceEngineersDedicated.exe. There is no Linux version from Keen. You will find people running it on Linux under Wine, a compatibility layer, but those recipes come from the community, and Keen publishes no Linux build or Linux instructions, so a game update can break one with no official fix.

So plan on Windows Server. On our machines it is a paid licence added to the bill each month, priced per core: flat up to eight cores, then per core above that. It also costs the same every month even if you prepay the server for longer. Windows needs an x86 machine; none of our ARM servers can run it.

How much machine your world needs

Keen lists two profiles. The core count stays at 3 logical cores in both; the jump is in speed and memory.

Bare minimum: a 3.2 GHz processor, 6 GB of memory and 5 Mbps of bandwidth.
Keen's recommendation: a 4.5 GHz processor, 10 GB of memory, and a fixed public IP if strangers will join.
Software: .NET 4.8 or newer, plus Microsoft's Visual C++ packages, versions 2013 and 2017.

Fall short of the minimum and, according to the official wiki, the server still starts but forces Experimental mode on. Keen gives no number per player or per ship. Since only the clock and memory rise between its two profiles, we would spend on a quicker processor before buying more cores, and treat the recommended figures as a starting point for a busy world.

Letting your friends in

Your players need a single door: UDP port 27016, the default listen port. Keen's instructions are to forward that UDP traffic to the server and allow it through its firewall. A rented server already has a public address, so you skip the router step and only add the Windows Firewall rule.

The settings file, SpaceEngineers-Dedicated.cfg, holds two more ports you should know about. SteamPort defaults to 8766 and isn't shown in the setup window. RemoteApiPort defaults to 8080 and carries the remote admin interface, which the official config reference shows switched on out of the box. Players never need that one, so don't open it to the internet; turn the API off if you won't use it.

Each port can belong to only one server instance. Want two worlds on one box? Give the extra instance different ports.

Up and running in an evening

Install the .NET and Visual C++ packages listed above.
Get SteamCMD from Valve, unzip it into a folder of its own, and run the command below. No Steam password is needed: Keen's command signs in anonymously.
Open SpaceEngineersDedicated.exe, pick Local/Console, give the server and the world a name, and press Save & start.
Want it to survive you logging out? Start the tool as Administrator and click Add new instance. That copy runs in the background as a Windows service.
Add a Windows Firewall rule allowing UDP 27016 in, then connect from your game.

steamcmd.exe +force_install_dir C:\SpaceEngineersDS +login anonymous +app_update 298740 +quit

Run the same line again whenever Keen ships an update. Valve's SteamCMD guide sets the install folder before signing in, and suggests its validate check only for a first install or broken files, because it overwrites anything you changed.

Keeping your world safe

Saved worlds sit in a SpaceEngineersDedicated folder, under either the server's ProgramData or your Windows user's AppData\Roaming. Bringing a single-player world across? Its folder is in AppData\Roaming\SpaceEngineers on your gaming PC; copy it over.

taskkill /IM SpaceEngineersDedicated.exe

That command, straight from Keen's guide, shuts the server down properly and saves first. Adding /f stops it instantly and throws away anything unsaved, so avoid it. Keen doesn't describe a backup routine, so here is ours: after a clean stop, copy the world's folder somewhere that is not this server.

Your remote admin key, RemoteSecurityKey in the settings file, signs every command the VRage Remote Client sends, and Keen's guide warns you to keep it to yourself. Treat it like the master password to your world. Your join password is stored in that file too (hashed and salted), another reason to keep it private.

The server that fits

Our game server hosting hands you one whole physical machine, so nobody else's game competes for the processor your world depends on. Choose by clock speed, since that is what Keen's figures reward; our Intel servers are listed by exact part number, so you can look each one up.

Nothing meters your port, and a busy weekend never shows up as an extra charge.
Three US cities and two in Europe: see the data center locations and pick the one closest to most of your crew.
Every rack server and blade includes a remote console, so you can still reach Windows if it won't start.
A machine already in a rack is usually yours in about 30 minutes once the order is approved; payment checks can add time.
Monthly, no contract, with people on the phone and in chat around the clock.

When something else suits you better

Most of our processors are older server chips at moderate speeds, chosen on purpose and priced that way. They won't match the 4.5 GHz Keen recommends, so a very large world will feel it. If you only need the server for a weekend event, an in-stock machine you rent by the hour may be the better fit. And if looking after Windows sounds like a chore, a managed game slot is simpler than a machine of your own.

Questions people ask

Will it run on Linux?: Not as Keen ships it: the server is built for Windows. Community guides run it under Wine, but Keen publishes no Linux build or Linux instructions, so you are relying on those guides when an update breaks something. Windows Server is the dependable route.
What do I forward so people can join?: UDP 27016, or whichever listen port you set. That is the only port Keen asks you to open. Keep the remote admin port, 8080 unless changed, closed to the public.
How many players can it hold?: You choose the cap in the settings, and the -maxPlayers start-up option overrides it. Keen doesn't publish hardware figures per player, so start from its recommended machine and watch simulation speed in the Remote Client as your crew grows.
Do I need to buy the game again for the server?: No. Keen says the dedicated server needs no licensed copy of its own, though it adds that getting the files takes a Steam account licensed for the game. Its own SteamCMD example fetches app 298740 signed in as anonymous.
Who pays for Windows?: You do, as its own monthly line: a licence priced per core, flat up to eight cores. Paying the server several months ahead does not discount it.

A Space Engineers dedicated server that keeps your world running