1. Find the world file
On Windows: %USERPROFILE%\AppData\LocalLow\Pugstorm\Core Keeper\Steam\<number>\worlds. Each world is <slot>.world.gzip, numbered by the slot it has in your game's world list.
2. Put it on the server
On your own server, stop it and copy the file into its data path's worlds folder, named after a slot, then start it with -world set to that slot.
On Flux, open the Worlds tab, choose the file under Bring Your Own World, pick a free slot and upload, then press Play on it. The world being played is saved and kept in its own slot.
Characters
Characters are not in the world: each player's character, inventory and skills are on their own computer and come with them to any server.
Frequently asked questions
Can I move my Core Keeper world to a dedicated server?
Yes: copy its .world.gzip file into the server's worlds folder (on Flux, upload it in the Worlds tab) and switch the server to that slot.
Do we lose our characters on a dedicated server?
No. Characters are kept by each player's game, not by the world, and join any server as they are.