How to Host a Core Keeper Dedicated Server: Setup and Configuration Guide

Core Keeper supports up to 8 players in cooperative underground exploration, and a dedicated server is the best way to keep your world available around the clock. This guide walks you through the full setup process, from installation through configuration, and explains when managed hosting makes more sense than self-hosting.

Why Run a Dedicated Server?

By default, Core Keeper uses a host-based multiplayer model. The world only exists while the host is playing, and other players cannot access it independently. A dedicated server solves this:

• Always online: Players can log in and continue progress at any time.
• Better performance: The server handles the world simulation separately from any player’s game client, reducing lag.
• Persistent progress: The world state (bosses defeated, buildings placed, resources mined) is always saved and available.
• Cross-storefront play: Since the August 2025 update, dedicated servers support players from Steam, Epic Games Store, GOG, and the Microsoft Store all connecting to the same world.

Self-Hosting on Windows

Step 1: Install the Server Tool

Open your Steam Library and switch to the Tools category. Search for “Core Keeper Dedicated Server” and install it. This is a free tool available to anyone with a Steam account.

Step 2: Launch and Generate a Game ID

Run the Core Keeper Dedicated Server tool. Make sure “Launch Dedicated Server” is selected and click Play. A command window will open, and the server will generate a Game ID. Players use this ID to connect through the in-game “Join Game” menu.

Write down the Game ID or share it with your group. It is unique to your server instance.

Step 3: Configure Server Settings

Close the server and open the ServerConfig.json file (located in the server’s installation directory). Key settings include:

Setting	Description	Default
world	World slot number to load	0
seed	World generation seed (0 = random)	0
maxPlayers	Maximum concurrent players	8
gamemode	0 = Normal, 1 = Hard, 2 = Creative, 3 = Casual	0
password	Server password (empty = no password)	""

Step 4: Choose a World Mode

The world mode determines combat difficulty and loot behavior:

• Casual: Reduced enemy health and damage. Good for newer players or groups focused on building.
• Normal: The standard experience balanced for small groups.
• Hard: Significantly increased enemy health and damage, but bosses drop more loot. Best for experienced groups of 4 or more.
• Creative: Unlimited resources for building without survival pressure.

You can change the world mode after creation, but keep in mind that switching mid-playthrough may affect group expectations.

Self-Hosting on Linux

For headless Linux servers (no GUI), use SteamCMD to download and manage the server files:

steamcmd +login anonymous +app_update 1963720 validate +quit

App ID 1963720 is the Core Keeper Dedicated Server. After installation, configure ServerConfig.json the same way as on Windows.

Launch the server with:

./CoreKeeperServer

Run it inside a screen or tmux session to keep it alive after you disconnect from SSH. Alternatively, create a systemd service for automatic startup and restart on crash.

Managed Hosting with Reactor

If you want a server running in minutes without managing hardware, operating systems, or manual updates, Reactor’s Core Keeper hosting is the simplest option:

• Instant setup: No installation steps. Your server is online and ready to accept connections immediately.
• Automatic game updates: Patches are applied as soon as they release.
• SFTP access: Full file system access for manual configuration when needed.
• Automatic backups: Scheduled daily backups with one-click restore protect your group’s progress.
• Cross-platform ready: The server supports all PC storefronts out of the box.

This is particularly valuable for groups that want to focus on playing rather than server administration.

Configuration Best Practices

World Seed Selection

If you want a specific world layout, share seed numbers with the community to find interesting generations. A seed of 0 gives you a random world each time, which is fine for most groups. Coordinate with your players before generating, since the world cannot be re-seeded without starting fresh.

Player Slots

Core Keeper supports up to 8 players on a single server. For the best experience:

• 2-4 players: The sweet spot for resource balance. The world generates enough materials for everyone without feeling sparse.
• 5-8 players: Works well but groups should coordinate mining directions to avoid depleting areas too quickly.

Backup Your World

The world data is stored locally on the server. If you are self-hosting, manually copy the save files on a regular schedule. Corruption or accidental deletion without a backup means starting over. Managed hosts like Reactor handle backups automatically.

Firewall and Network

If self-hosting, ensure the server port is open in your firewall. Core Keeper dedicated servers communicate through Steam’s relay system by default, which simplifies networking. However, if you experience connection issues, verify that your firewall is not blocking the server executable.

Updating Your Server

Core Keeper receives regular patches. After each update:

1. Stop the server gracefully.
2. Update through Steam or SteamCMD (+app_update 1963720 validate).
3. Restart the server.
4. Verify all players can connect and mods (if any) are compatible.

On managed hosting, this process is automatic. On self-hosted setups, consider a cron job or script that checks for updates on a schedule.

A dedicated Core Keeper server turns a great cooperative game into a persistent world your group can explore together over weeks and months. Set one up through Reactor or follow the self-hosting steps above, and start digging.