No Man’s Sky has evolved over many years, so older profile directories can contain naming conventions that differ from current saves. That makes destructive cleanup risky. Archive the whole NMS directory before renaming or moving anything, and keep Microsoft Store WGS data separate from normal desktop .hg files. A future game-specific tool should identify the exact generation and container before writing; Phase 23 only documents the storage and backup boundaries.
Known No Man's Sky save-file structure
The researched filename or folder pattern is save*.hg
mf_save*.hg (current/metadata family; older installs may contain storage*.hg names). File-extension context: .hg The documented format notes are: No Man's Sky uses profile-scoped .hg save records. The Microsoft Store/Xbox app build uses WGS instead of the same visible Steam/GOG-style files.
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. Older 2016/2017 file naming and current save naming can differ. Do not rename historical .hg files blindly without retaining the originals. 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: %APPDATA%HelloGamesNMS
Microsoft Store: %LOCALAPPDATA%PackagesHelloGames.NoMansSky_bs190hzg1sesySystemAppDatawgs | macOS: $HOME/Library/Application Support/HelloGames/NMS/ | Linux / Steam Play: Steam Play: <SteamLibrary-folder>/steamapps/compatdata/275850/pfx/. Storefront context: Steam, GOG Galaxy, Microsoft Store / Xbox app. Desktop storefront files and Microsoft WGS containers are different migration surfaces. Older installations can also contain legacy storage*.hg naming. 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
Copy the entire NMS profile directory, including metadata companions, before editing or migrating. For Microsoft Store, preserve the WGS container separately. A read-only viewer is lower risk than a writer, but the live save should still be copied first. Cloud context also matters: Storefront cloud support can synchronize the same profile. Cross-platform/cross-save features should be treated as service workflows rather than proof that arbitrary local files are byte-compatible. 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 an older save is not listed, first preserve every .hg record and compare modification times. PCGamingWiki documents historical storage-to-save rename cases, but any rename attempt should be reversible. Those questions require a verified parser/profile or a game-specific source, not a generic format guess.
Verification context: Windows/macOS/Microsoft Store/Steam Play locations and historical .hg naming notes were reviewed against current PCGamingWiki coverage.