NotAlterra

Subnautica 2 save-file manager — cross-platform terminal application.

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.

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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

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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

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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

Menu

1. Recover .sav from .bak — pick a backup, preview metadata, overwrite the live save
2. Create full backup — copies all savegame_* files to NotAlterra_Backups
3. Restore full backup — overwrite the save folder from a previous backup
4. Inspect save files — view all GVAS properties of any .sav / .bak
5. Manage UE5 Config (.ini) files — backup, restore, or delete .ini files
6. View disclaimer
7. Exit

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Where Files Live

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

Backups are stored in NotAlterra_Backups\ alongside the binary.

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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.

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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

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License

MIT — see LICENSE.md.