Core Keeper Server Launch Arguments and Mods

What public copies of the arguments file keep repeating

Stop with Q, and copy ServerConfig.json plus the worlds folder. Most settings can live in ServerConfig.json. Public copies of ARGUMENTS.txt say -port and -ip are not read from that file, only from the command line. Open yours before you park those two in JSON.

Families those copies list, which you should match line by line:

• -world selects the slot. -worldname is the name clients see.
• -worldseed applies only when the world is created. -worldmode names Normal, Hard, Creative and Casual. Switching between creative and the other modes later is not described as supported.
• -gameid pins the join code. A rejected value is replaced with a random ID, so players suddenly have a different code. Length and forbidden characters are in the file.
• -password is for direct connections, not for the Game ID. Those copies mention a 28-character maximum.
• -port switches the server to direct connections. Without it, the Steam relay is enough and that README does not ask for a forward.
• -maxplayers sets the cap. The local file has the default. A higher number is described there as heavier, not as free.
• -allowonlyplatform is Steam, Epic, Microsoft or GOG in those copies, and it turns crossplay off. Without -port, it does nothing.
• -datapath moves saves. The wiki default is still the DedicatedServer folder under LocalLow.
• -season forces an event. -activatecontent turns content bundles on permanently. Those copies say you cannot undo it for that world.

Do not try -activatecontent on the group's main world. Use an empty -world index.

Install mods on the dedicated server

A Core Keeper dedicated server does not download the client's mod.io subscriptions. Stop it with Q, copy the worlds folder, then use Download File on each mod's mod.io page.

Create this folder inside the server install if it does not exist:

<server-install-folder>/CoreKeeperServer_Data/StreamingAssets/Mods/

Extract every mod into its own subfolder. Each subfolder must contain a ModManifest.json file at its top level. Read the mod page and install its dependencies the same way because the dedicated server does not resolve them for you.

Build the mod set on the server first. To prevent version drift, the documentation recommends zipping that folder and giving players the same copy to extract into CoreKeeper_Data/StreamingAssets/Mods/. Players should unsubscribe from the automatic mod.io copies when they use this manual method.

Test one mod at a time on a copy of the world. After each addition, confirm that the server still writes GameInfo.txt, prints a join code and accepts a client with the same versions. If startup fails, remove the last folder and restore the backup if the world no longer loads.

Check which network mode you actually started

Without -port, a Steam player joins with the Game ID and you do not open a port for that. With -port, the firewall and the forward target that port, and a player on another PC store should be able to type IP, port and password. When the build writes GameInfo.txt, it lists platforms, IP, port and password. Compare it with the command you think you launched.

Offers: Core Keeper comparison.

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