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.
Choose the correct backup boundary
For Oxygen Not Included, the researched PC save location is Windows: Local: %USERPROFILE%DocumentsKleiOxygenNotIncludedsave_files ; Steam cloud: %USERPROFILE%DocumentsKleiOxygenNotIncludedcloud_save_files<user-id>. The known save file or folder pattern is Colony save files beneath save_files or the Steam cloud_save_files account directory.. 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. Copying the complete documented save boundary is safer than selecting one visually obvious file, because companion metadata, indexes, backups, or multiple slots can be required together.
Make an offline copy before changing anything
Close the game first, wait for the active launcher to finish writing, then copy the save data to a separate folder that the game and sync client do not watch. Label the copy with the game, storefront, profile, and date. Documented launcher context: Steam, Epic Games Launcher. 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.
Account for cloud saves
Steam Cloud and Epic cloud are documented; OneDrive can also synchronize Documents if enabled. Before restoring an older backup, decide which copy should win. If the game or launcher starts while an older manual copy is in place, synchronization can replace it before you confirm that it works. Keep the untouched backup outside the live save path until the restored progress has been opened and saved normally.
Restore without changing format assumptions
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. Compatibility note: Save compatibility can depend on game updates and DLC branch. A local and cloud copy with the same colony name can represent different timestamps. Restore into the matching storefront/profile context whenever possible. Do not rename a save extension, move a folder into a different container type, or assume a console/mobile copy is equivalent unless a tested migration path specifically says so.
Recovery fallback
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. If the restored copy fails, put the untouched original back first. Then compare location, account/profile, cloud state, and the full directory structure before trying a different backup. The objective is reversible recovery, not repeated destructive experiments on the only copy.
Verification context: Reviewed against current PCGamingWiki Oxygen Not Included save-location/cloud documentation.