NotAlterra is an unofficial tool for managing Subnautica 2 save files. It locates your save folders, backs up and restores .sav / .bak files, and lets you inspect the internal metadata of every save.

Not affiliated with Unknown Worlds Entertainment or KRAFTON.

Features

Manual path entry — set your save folder from the menu (paste supported)
Recover a corrupted .sav from its .bak backup with rollback
Create / restore full backups (only savegame_* files)
Manage UE5 Config .ini files — backup, restore, delete
Inspect any .sav or .bak file — full GVAS metadata dump
Slot grouping with Multiplayer / Single Player detection
Playtime extraction — displays total playtime from save metadata
Warns on name changes and mode switches before recovery
Startup reminder to close Subnautica 2 before use
Transaction log — all actions timestamped to transaction.log
Cross-platform — Linux and Windows console builds
Developer Documentation — auto-generated from source

How to Build

# Linux
cargo build --release

# Windows (from Linux with mingw-w64)
rustup target add x86_64-pc-windows-gnu
sudo apt install mingw-w64
cargo build --release --target x86_64-pc-windows-gnu

How to Run

Download the pre-compiled executable for your platform from the releases page.

Linux

tar -xzf notalterra-v0.1.3-linux-amd64.tar.gz
chmod +x notalterra
./notalterra

Windows

Extract the .zip archive and double-click NotAlterra.exe, or run from a terminal:

Expand-Archive notalterra-v0.1.3-windows-x64.zip -DestinationPath .
.\NotAlterra.exe

You can also extract the .zip using Windows Explorer (right-click → Extract All), then open Command Prompt or PowerShell in that folder and run .\NotAlterra.exe.

Important

Running an unsigned executable on Windows triggers a UAC "Unknown Publisher" warning, forcing you to click "Run anyway" and bypass Windows' safety net. This tool lacks a signature not because it's unsafe, but because services like SignPath Foundation require a well-established CI/CD pipeline, audit trail, provenance documentation, and community standing to meet their acceptance criteria.

Usage

Run the binary. Use Set save folder from the main menu to enter your save path manually (paste is supported). The menu is keyboard-driven:

Key	Action
`↑` `↓`	Navigate
`Enter`	Select
`Esc`	Cancel / Back
`Y` / `N`	Accept / Decline in dialogs

Set save folder — enter your save folder path manually (paste supported)
Recover save file — pick a backup, preview metadata, overwrite the live save
Create full backup — copies all savegame_* files to NotAlterra_Backups
Restore full backup — overwrite the save folder from a previous backup
Inspect save files — view all GVAS properties of any .sav / .bak
Manage UE5 Config (.ini) files — backup, restore, or delete .ini files
View disclaimer
Exit

Where Files Live

%LOCALAPPDATA%\Subnautica2\Saved\SaveGames\
    savegame_0.sav
    savegame_0.bak
    savegame_0_1.bak
    savegame_1.sav
    ...

Linux (Proton / Steam Deck)

~/.steam/steam/steamapps/compatdata/1962700/pfx/drive_c/users/steamuser/AppData/Local/Subnautica2/Saved/SaveGames/
    savegame_0.sav
    savegame_0.bak
    ...

Use Set save folder from the menu to enter your save path. The path is persisted in config.ini for re-use across sessions. Delete the config file or use the menu option again to change it.

Backups are stored in NotAlterra_Backups\ alongside the binary.

config.ini

Created automatically next to the binary:

[alterra]
save_path = C:\Users\...\Subnautica2\Saved\SaveGames
save_scan = 2026-05-31 18:00:00
disclaimer_accepted = true
ini_path = C:\Users\...\Subnautica2\Saved\Config\Windows

Delete config.ini to clear the cached path — you will be prompted to set a new one on next launch.

Only the disclaimer flag and save-folder paths are stored — no backup state or file metadata is persisted.

Platform Support

Windows — fully tested and supported.
Linux — builds and runs. Use Set save folder to enter your save path (typical Proton locations are shown under "Where Files Live" above).

Safety

Runs in your user context — no admin privileges required
No network connections
Read-only inspect mode won't touch files
Pre-restore snapshots created automatically
.ini delete requires a prior backup

License

MIT — see LICENSE.md.

README.md

NotAlterra