Core Keeper Dedicated Server: Setup, Joining by IP and Saves

A Core Keeper dedicated server keeps your underground world running when the host logs off, so everyone can mine, farm and fight bosses on their own schedule. This guide covers self-hosting Pugstorm's server, running it on our Core Keeper server hosting, the settings, how friends join and how to move a world.

• Two ways to join: by default the server uses Steam's relay network and players join with a Game ID. Started with a port, it accepts direct connections by IP, port and password instead.
• Who can join: PC players on Steam, Epic Games, GOG and the Microsoft Store. Console players cannot join a PC server.
• Players: Pugstorm supports 1 to 8 players per world on PC. The server can go higher, at your own risk.
• On 1up: Core Keeper needs at least 3 GB of RAM, so it runs on Free with the hourglass at ×1.5 and 24/7 from Starter. Players join with the IP and port from the panel plus the password you set.

1. Self-host or hosting?

A dedicated server is a separate program that holds the world, so nobody has to keep the game open for the others. Pugstorm ships it for free as Core Keeper Dedicated Server (Steam app 1963720), for Windows and Linux.

• Host from the game: free and built in. The host presses Escape, copies the Game ID and sends it to friends, as Fireshine's support FAQ explains. The world only exists while the host plays.
• Self-host the dedicated server: free, full control, and your PC stays on.
• A hosted server: the world runs in a data centre and you manage it from a web panel.

To self-host, the official Core Keeper wiki gives two install routes: the Steam client (the server shows up in your library's Tools) or SteamCMD with an anonymous login:

steamcmd +force_install_dir c:\corekeeperdedicatedserver\ +login anonymous +app_update 1963720 +quit

Run Launch.bat on Windows. The server opens a PowerShell window that prints the Game ID (also saved in GameID.txt) and stays open while the server runs. Press Q in that window to stop it; the wiki warns that closing the window leaves the server process running.

In this default mode the server talks through Steam's relay network, so you forward no ports. If you want friends to join by IP instead, add -port to the launch arguments and open that UDP port on your router. The ARGUMENTS.txt file that ships with the server since update 1.1.0 documents every option.

2. Create a Core Keeper server on 1up

This is the route we built for groups that want a world online 24/7 without a PC left on.

1. Create an account and press Create server.
2. Choose Core Keeper. On Free it runs with the hourglass at ×1.5 (your free time drains 1.5 times faster); Starter and up keep it online 24/7.
3. Pick a region, London or Paris. The wizard measures your ping and suggests the nearest one.
4. On the configure step, pick the world mode, leave the seed empty for a random world, and set a password.
5. Create the server. The world is generated on the first start, and the server always installs the latest public build from Steam when it boots.
6. When it is online, the Overview shows two lines: Subdomain and IP. The IP line holds the address and port your friends need.

3. The panel settings

The Game tab holds four Core Keeper settings. Each one maps to a launch argument from the game's ARGUMENTS.txt, and each applies on restart.

A few notes from running it:

• Always set a password. Players joining by IP need one, and when the server starts without one, the game generates a random password for the session that our panel does not show. Pick your own before you invite anyone.
• Max players above 8. Fireshine's FAQ supports 1 to 8 players on PC. The server accepts a higher number, but ARGUMENTS.txt warns that more players may need more resources or make the session unstable.
• World mode belongs to the world. ARGUMENTS.txt says that switching between Creative and the other modes after the world exists is not supported. Choose it before the first start.
• The seed only counts once. It is used when the world is created. Since patch 1.0.0.6, the server takes text seeds the same way the game client does. To play another seed, use Regenerate world under Server → World, which deletes the current world and can take a backup first.
• Seasonal events follow the date. We do not pass a season, so the game sets it from the system date, as ARGUMENTS.txt describes.

4. Invite friends: Game ID or IP

Core Keeper has two join paths, and which one works depends on how the server was started.

• Game ID: the default. A code of 15 to 28 characters that friends paste into Join Game. It goes through the relay, so it works without port forwarding.
• IP, port and password: since patch 1.1.2.3 of August 2025, a server started with -port "can now be joined using the servers IP, Port and Password". Pugstorm's announcement explains why it exists: PC players on Steam, Epic Games, GOG and the Microsoft Store can now share one dedicated server.

Our servers run in direct-connect mode. So on 1up:

1. Copy the IP line from the Overview, for example 203.0.113.10:31234. The port is not 27015 on our nodes, so take both numbers from the panel.
2. Share it with your password.
3. In Core Keeper, each player opens Join Game, chooses to join by IP and enters the IP, the port and the password.

Use the numeric IP line, not the Subdomain, because the game asks for an IP address. Players outside Steam may also need cross-play turned on in their gameplay settings, according to Fireshine's FAQ.

Consoles are a hard limit. The FAQ says Core Keeper "ONLY supports cross-play between PC platforms" and that there are no plans for console-to-PC cross-play, so PlayStation, Xbox and Switch players cannot join a PC dedicated server, hosted or not.

5. Move your world and keep backups

The server keeps its data in the folder set by -datapath. On our servers that is save/, and the world is save/worlds/0.world.gzip, since the server loads world slot 0.

On a Windows PC, the wiki gives the client world folder as %APPDATA%\..\LocalLow\Pugstorm\Core Keeper\Steam\<your Steam ID>\worlds\, with one numbered .world.gzip file per slot. To bring a world over:

1. Stop the server and take a backup in the Backups tab.
2. Open Files, go to save/worlds and upload your world file, named 0.world.gzip. If your world sits in another slot, rename the copy. The file manager does not unzip anything, and the file stays compressed as the game wrote it.
3. Start the server and watch the Console. If the world name and progress look wrong in game, restore the backup.

We have checked that our image writes save/worlds/0.world.gzip when it stops. We have not yet tested an upload of a client world, so keep that backup until everyone has logged in.

A stop from the panel sends the signal the game saves on. The wiki notes that a new server writes its worlds folder about 30 seconds after the first player logs in. Starter keeps 3 backups and Pro keeps 5. Take one before a big boss fight or an update.

6. Limits worth knowing

Core Keeper is a quiet server to run, but some things are out of reach on 1up today:

• No console commands. The game has no RCON or command console, so the Console tab shows the log, who is online and the server status. Admins and bans live in two files, save/Admins.json and save/PlayerBans.json, which the Players tab points to and Files edits. Change them with the server stopped.
• No Game ID join. Our servers use direct connections, so friends join by IP, port and password.
• No content bundles. The -activatecontent option that adds optional content to an existing world is not in the panel.
• Vanilla only. Core Keeper runs the Vanilla template; there is no mod loader in the panel.
• PC only. Console players cannot join, as section 4 explains.

For the RAM, Core Keeper needs 3 GB to start on 1up, and we recommend 6 GB for an explored map full of automation. With prices from our pricing page, Starter (€5/month) gives 4 GB of RAM, 20 GB of disk and 10 player slots; Pro (€10/month) gives 8 GB, 60 GB and 30 slots, above the 6 GB we recommend.

If your group also plays other survival games, our guides to a Valheim dedicated server and a Necesse dedicated server follow the same steps.

Tested on Core Keeper 1.3.0.4 (dedicated server build 25625045), 2026-10-06: settings, files and join path checked against our image on 1up v0.245.0. Our image starts the server and saves the world on stop; no game client has joined it on our cluster yet.

Change log

• 2026-10-06: first version, after patch 1.3.0.4.
• 2026-10-08: panel names updated: the Game and Server tabs replace the old Settings tab.
• 2026-10-20: Free now runs Core Keeper with the hourglass at ×1.5.
• 2026-10-26: current Starter and Pro figures (€5/4 GB, €10/8 GB/30 slots).