For New Vegas, the save file is only part of a reproducible modded setup. Back up the entire Saves folder and separately record the active mod list before changing load order or moving progress to another PC.
Known Fallout: New Vegas save-file structure
The researched filename or folder pattern is *.fos save files plus paired metadata/backup artifacts when present. File-extension context: .fos The documented format notes are: New Vegas uses Bethesda Gamebryo save records with the .fos extension. Mods, DLC, load order, and script state can be embedded in progress, so a byte-level file match does not guarantee a safe modded restore.
Why an extension is not enough
A save filename can identify a likely container, but it does not prove the internal schema, game version, checksum rules, encryption state, or editability. Treat saves as version-, storefront-, account-, and mod-sensitive unless the game or a separately verified migration workflow proves otherwise. A similar filename or extension is not evidence that two releases are interchangeable. SaveEditor therefore separates file identification from Tool compatibility and only labels a game-specific Tool Verified when its exact profile/version evidence passes the runtime gate.
Where the format is stored
PC save locations: Windows: %USERPROFILE%DocumentsMy GamesFalloutNVSaves. Storefront context: Steam, GOG, Epic Games Store, Microsoft Store. The active Steam, GOG, Epic Games Store, Microsoft Store installation determines which local profile and cloud copy can overwrite the save. Identify the storefront and account before restoring files. This matters because two releases can use different containers or companion files even when the visible slot name is similar.
Back up before inspecting or editing
Close Fallout: New Vegas, let the launcher finish any synchronization, then copy the complete documented save directory to a dated folder outside the live path. Preserve companion files rather than selecting only the newest-looking record. A read-only viewer is lower risk than a writer, but the live save should still be copied first. Cloud context also matters: Cloud support differs by storefront; keep an offline copy of the Saves folder and the mod/load-order context for modded games. Keep the original bytes available so any experiment can be reversed without relying on a cloud service or automatic backup.
What this reference does not claim
This page does not infer an undocumented checksum algorithm, encryption key, compression layer, or cross-store conversion from the file extension. Troubleshooting evidence: If progress is missing after a restore, confirm the active Windows account, storefront/profile, cloud state, and exact directory first. Restore the untouched backup before experimenting with individual files or older autosaves. Those questions require a verified parser/profile or a game-specific source, not a generic format guess.
Verification context: Windows save location, file-boundary, launcher/cloud, and backup notes were reviewed against the linked game-specific references for Fallout: New Vegas. This Game Hub is documentation only and does not claim a new game-specific Save Editor.
Recorded Phase 40 evidence boundary
This Phase 40 entry is grounded in the researched PC save boundary for Fallout: New Vegas: Windows: %USERPROFILE%DocumentsMy GamesFalloutNVSaves The recorded file or folder pattern is *.fos save files plus paired metadata/backup artifacts when present. These concrete identifiers are retained so backup, transfer, recovery, and editing preparation remain tied to the documented game/storefront context instead of a generic extension guess.