Hearth syncs your Core Keeper world saves through Google Drive automatically. Every tile explored, every boss defeated, every farm planted — available to anyone in your crew, any time the host is offline.
Up to eight players can dig together — but the world save lives on the host's machine. When they go offline, the entire underground is sealed.
Your group has been systematically expanding the underground, farming ancient seeds, and pushing toward new bosses. Then the host disappears. Every bit of that incremental progress is locked away until one specific person logs back in.
Core Keeper saves worlds as numbered .gzip files — 0.world.gzip, 1.world.gzip — with no readable world names. Sending the right numbered file to the right player, in the right slot, without overwriting a different world, requires careful steps most players get wrong at least once.
Core Keeper's own wiki warns that Steam Cloud can revert saves unexpectedly. If changes you make are being rolled back after sessions, Steam Cloud is likely overwriting your local save with an older version from the cloud.
Hearth handles the .gzip world files automatically. No numbered file juggling, no slot confusion, no accidental overwrites.
Right-click Core Keeper in Steam → Properties → General → uncheck "Keep game saves in the Steam Cloud." This prevents Steam from reverting your saves between sessions.
Open Hearth, find your Core Keeper world, and check the share box. Hearth pushes the world file to your shared Google Drive folder. Your group sees it on their end within seconds — no numbered file confusion.
When Core Keeper launches, Hearth locks the shared world and pulls the latest version from Drive automatically. You're always starting from the freshest save.
When Core Keeper closes, Hearth pushes the updated world to Drive. The next player pulls it automatically when they open Hearth. The underground is always ready for whoever logs on next.
No server setup. No numbered file confusion. No Steam Cloud save reversions. Just your underground world, always available to whoever wants to dig.
Hearth handles the numbered .gzip world files automatically. No figuring out which 0.world.gzip goes in which slot on whose machine.
When Core Keeper launches, Hearth locks the shared world. No accidental overwrites while someone is mid-session in the caverns.
Local backups every 25 minutes while you play. Never lose more than 25 minutes of farming, mining, or boss prep.
Saves go to your own Google Drive, not Steam's servers. No subscription, no account with us. You control your world files.
Every line of code is public on GitHub. Read exactly what Hearth does with your save files before you run it.
No trial. No premium tier. Free because incremental underground progress shouldn't be gated behind one person's schedule.
%USERPROFILE%\AppData\LocalLow\Pugstorm\Core Keeper\Steam\[YourSteamID]. Worlds are saved as numbered .gzip files like 0.world.gzip inside a worlds folder. Hearth finds the correct path automatically based on your Steam ID.Free download. Open source. Five minutes to set up. No account required on our end — just a Google Drive folder your group shares.
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