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

Auto-locate save folders across Steam, Xbox, Epic, and custom installs
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 Online / Local detection
Warns on name changes and online↔local mode switches before recovery
Game-running guard — exits or warns if Subnautica 2 is active
Transaction log — all actions timestamped to transaction.log
Cross-platform — Linux and Windows console builds

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 archive for your platform from the releases page.

Linux

tar -xzf notalterra-v0.1.0-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-v0.1.0-windows-amd64.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.

Usage

Run the binary. On first launch it auto-scans for your save folder. The menu is keyboard-driven:

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

Recover .sav from .bak — 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
    ...

For older Steam installs, replace ~/.steam with ~/.local/share/Steam — NotAlterra checks both.

Backups are stored in NotAlterra_Backups\ alongside the binary.

config.ini

Created automatically next to the binary:

[alterra]
last_path = C:\Users\...\Subnautica2\Saved\SaveGames
last_scan = 2026-05-31 18:00:00
disclaimer_accepted = true
config_path = C:\Users\...\Subnautica2\Saved\Config\Windows

Delete config.ini to force a fresh scan on next launch.

Platform Support

Windows — fully tested and supported.
Linux — builds and runs, but automatic save-file detection has not been tested on a Linux/Steam Deck install yet. The directory layout should be the same, but feedback and bug reports are appreciated.

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
Guard against file corruption: refuses overwrite if Subnautica 2 is running

License

MIT — see LICENSE.md.

README.md

NotAlterra