NotAlterra

Subnautica 2 Save Manager

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

Menu

1. Set Subnautica 2 location — enter your save folder path manually (paste supported)
2. Recover save file — pick a backup, preview metadata, overwrite the live save
3. Set backup location — choose where backup archives are stored (default: ~/NotAlterra)
4. Create full backup — copies all savegame_* files to the backup root
5. Restore full backup — overwrite the save folder from a previous backup
6. Manage UE5 Config (.ini) files — backup, restore, or delete .ini files
7. View disclaimer
8. 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).

Backup Types

NotAlterra creates two kinds of save backups. The label in the restore picker tells you which is which.

Label	How it's created	Purpose
Full Backup — <date>	Manual — via Create full backup in the main menu.	Your own snapshot of the save folder. Create one before trying something risky.
Pre-restore — <date>	Automatic — created just before a Restore full backup operation.	Safety net — ensures your current saves are never lost when restoring an older backup.

When you use Restore full backup, NotAlterra automatically takes a safety snapshot of your current saves before it does anything. This Pre-restore backup is not a replacement for manual backups — it is an automated safety net in case the restore doesn't go as expected.

If the restore goes wrong, your old saves are still there in the restore picker labeled Pre-restore — <date>. You can restore from that snapshot just like any other backup.

Pre-restore snapshots are never deleted automatically. Once you're happy with the restore, you can delete them manually from the file system.

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.