Oxygen Not Included can keep local and Steam-cloud colony files in neighboring but different Documents directories. That makes backup deceptively easy: copying only save_files may miss the actively synchronized colony, while copying only cloud_save_files may omit a local-only game. SaveEditor recommends preserving both trees before changing cloud settings and using timestamps plus the game build/DLC context to decide which copy is authoritative. This is safer than assuming the copy with the most familiar folder name is the newest.
For this PC reference, the documented storage is Windows: Local: %USERPROFILE%DocumentsKleiOxygenNotIncludedsave_files ; Steam cloud: %USERPROFILE%DocumentsKleiOxygenNotIncludedcloud_save_files<user-id>. The known file or folder pattern is Colony save files beneath save_files or the Steam cloud_save_files account directory.. Oxygen Not Included distinguishes local save_files from Steam cloud_save_files. Both live below the Klei Documents tree, so the active copy can depend on whether cloud saving is enabled for that colony.
Backup guidance: Back up both save_files and the relevant cloud_save_files user directory before changing cloud settings or moving a long-running colony. Label the copy with game build/DLC branch. Steam Cloud and Epic cloud are documented; OneDrive can also synchronize Documents if enabled. Launcher and cloud context matters because Do not assume save_files is the active source when Steam cloud is enabled; the user-specific cloud_save_files directory may contain the copy being synchronized.
Compatibility and recovery should stay conservative. Save compatibility can depend on game updates and DLC branch. A local and cloud copy with the same colony name can represent different timestamps. If the expected progress is not visible, If a restored colony is replaced, compare local versus cloud timestamps and resolve Steam/OneDrive synchronization before launching again. Avoid repeatedly overwriting both trees at once. SaveEditor.com only labels a game-specific editor as available when a separate linked Tool has a verified operational runtime; this reference page by itself is not an editor claim.