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 (read-only — not stored, not tracked; helps the user identify which savegame backup they are dealing with)
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
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 Subnautica 2 location from the menu to enter your save path (paste supported). The path is persisted to app.ini and restored on next launch.

Session Persistence

Configuration is stored in the standard platform config directory:

Platform	Config path
Windows	`%LOCALAPPDATA%\NotAlterra\config\app.ini`
Linux	`~/.local/share/NotAlterra/config/app.ini`

The app.ini file stores your save-folder path, backup location, and disclaimer acceptance. It is auto-created when you first set any of these options. Delete NOTALTERRA_LICENSE_ACCEPTED in the same directory to re-prompt the disclaimer on next launch.

Privacy note: app.ini stores your save-folder and backup paths — the minimum needed to avoid re-entering them each session. These paths may reveal your system username (e.g. C:\Users\jane\...). The information never leaves your machine — NotAlterra has no network access and no telemetry. The file is plain text; you can inspect or delete it at any time.

Backup archives are stored in your user data directory by default:

Platform	Backup root
Windows	`C:\Users\<you>\NotAlterra\backups\saves\`
Linux	`~/NotAlterra/backups/saves/`

UE5 Config .ini backups go into backups/ue5/ under the same root.

You can change the backup root at any time via Set backup location in the main menu. The path is persisted in app.ini.

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