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An Anime Game Launcher automatically detects when game updates are available and handles the download and installation process.

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Update Detection

The launcher checks for updates every time it starts and periodically while running. What gets checked:
  • Base game version
  • Voice pack versions (for all installed languages)
  • Predownload availability (early access to upcoming updates)
Launcher states:
  • Launch - Game is up to date
  • Update Available - New version ready to download
  • Not Installed - Game needs initial download
  • Predownload Available - Next version available early

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Installing Game Updates

1

Update Notification

When an update is available, the main launcher button changes:
  • Icon changes to download symbol
  • Button text shows “Update” or “Download”
  • Version information displays current and target versions
The launcher detects updates by comparing:
  • Local .version file in game directory
  • Remote API version information
  • Voice pack version files
The launcher prioritizes the parsed game version over API responses (changed in version 3.11.0).
2

Start Download

Click the main action button to begin downloading.What happens:
  1. Launcher calculates required download size
  2. Checks available disk space
  3. Verifies temp folder configuration
  4. Begins downloading update files
Download method:
  • Uses Sophon technology (multi-threaded downloads)
  • Thread count configurable in settings
  • Downloads to temp folder before applying
Sophon support was added in version 3.14.0 and significantly improves download speeds through multi-threading.
3

Monitor Progress

The launcher shows detailed progress information:Progress bar displays:
  • Current download status
  • Download speed
  • Percentage complete
  • Estimated time remaining (when available)
Status messages:
  • “Downloading…” - Fetching update files
  • “Unpacking…” - Extracting archives
  • “Applying patches…” - Installing hdiff patches
  • “Removing outdated files…” - Cleaning up old versions
  • “Updating permissions…” - Setting file permissions
The download process is defined in src/ui/main/download_diff.rs.
4

Apply Update

After downloading, the launcher automatically:
  1. Unpacks archives - Extracts downloaded files (7z or segmented archives)
  2. Applies patches - Installs hdiff differential patches
  3. Updates files - Replaces old files with new versions
  4. Removes outdated files - Cleans up deprecated game files
  5. Updates permissions - Sets executable permissions (chmod 755)
  6. Verifies installation - Checks game integrity
Do not interrupt the update process while “Applying patches” or “Removing outdated files” is shown. This can corrupt your game installation.
5

Update Complete

When finished:
  • Progress bar shows 100%
  • Main button returns to “Launch” state
  • Game is ready to play
If errors occur:
  • Toast notification shows error details
  • Check console output for full error messages
  • Partial downloads can be resumed
  • See Troubleshooting below

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Predownloading Updates

Predownload allows you to download the next game version before it’s officially released.

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When Predownload is Available

Predownload button appears when:
  • Game publisher makes next version available early
  • Current game version is up to date
  • Predownload hasn’t been completed yet
Button location: A circular button with a save icon appears next to the main launch button. Tooltip shows:
  • Target version number
  • Total download size (game + voice packs)

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Predownload Process

1

Start Predownload

Click the predownload button (save icon) to begin.What downloads:
  • Base game update files
  • All installed voice pack updates
The launcher downloads to: {temp_folder}/updating-{component_id}/
2

Download in Background

Predownload works like regular updates:
  • Shows progress in the progress bar
  • Downloads can be paused/resumed
  • Uses Sophon multi-threading
Completion marker: When finished, the launcher creates .predownloadcomplete files in each component’s temp folder.
3

Predownload Complete

After completion:
  • Predownload button shows success state (green checkmark)
  • Button becomes disabled
  • Files are ready to apply when update goes live
4

Apply Predownloaded Update

When the update officially releases:
  • Main button shows “Update” action
  • Clicking it applies the predownloaded files
  • Installation is much faster (only unpacking/patching)
Predownloaded files remain in the temp folder until the update is applied. Make sure you have sufficient disk space.

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Predownload States

Button StateMeaning
Warning icon (orange)Predownload available, not started
Success icon (green)Predownload complete, ready to apply
DisabledPredownload complete or not applicable
HiddenNo predownload available

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Voice Pack Updates

Voice packs update independently from the base game. Update behavior:
  • Launcher checks all installed voice packs
  • Downloads only outdated packs
  • Updates apply after game update (if both available)
Voice pack update process:
  1. Download voice pack diff to temp folder
  2. Unpack archive
  3. Apply to voice pack directory
  4. Verify installation
Voice packs are stored in subdirectories within the game folder and use the same update mechanism as the base game.

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Update Configuration

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Temp Folder

Configure where updates are downloaded: Settings path: Settings > General > Temp Folder Recommendations:
  • Use a fast drive (SSD preferred)
  • Ensure sufficient space (20+ GB recommended)
  • Avoid network drives
Default location: /tmp or system temp directory

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Sophon Threads

Control download performance: Settings path: Settings > General > Sophon Threads Recommendations:
  • Default: 4 threads
  • Fast connections: 8-16 threads
  • Slow connections: 2-4 threads
Sophon threads configuration is at config.launcher.sophon.threads and was introduced in version 3.15.0.

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Troubleshooting Updates

Fixed in version 3.15.3If you experience this:
  1. Update your launcher to 3.15.3 or later
  2. Wait a few minutes - the launcher may be verifying files
  3. Check console for error messages
  4. Restart the launcher if truly stuck
This was a known issue fixed in the changelog: “Fixed update getting stuck at 100% or close.”
Fixed in version 3.15.5Symptoms:
  • Download reaches 100%
  • Starts again from 0%
  • Repeats endlessly
Solution: Update to launcher version 3.15.5 or later.
Fixed in version 3.15.6If you see this error:
  1. Update your launcher
  2. Verify game installation path is correct
  3. Check that .version file exists in game directory
  4. Try running game repair from the menu
Fixed in version 3.15.2Previous issues:
  • Preload progress bar not displaying
  • Preload stuck on wait condition
  • Voice pack preloaded data deleted during update
Solutions:
  1. Update to 3.15.2 or later
  2. Clear temp folder: {temp}/updating-*
  3. Restart predownload
Fixed in version 3.15.1Check your configuration:
  1. Go to Settings > General
  2. Verify Temp Folder path
  3. Update launcher to 3.15.1+
  4. Restart launcher
Added support in version 3.9.1If extraction fails:
  1. Ensure you have 7z installed: which 7z or which 7za
  2. Check temp folder permissions
  3. Verify sufficient disk space (2x the download size)
  4. Check console for detailed error messages
Segmented zip archives (multi-part downloads) are automatically detected and handled.
Required space:
  • Download size (shown in UI)
  • Unpacked size (usually 2-3x download)
  • Final installation size
Total formula: Required = (Download × 2) + InstallationSolutions:
  1. Free up disk space
  2. Change temp folder to a drive with more space
  3. Remove old Wine/DXVK builds from Settings
  4. Clear system temp files
Common error types:DownloadingError:
  • Network connectivity issues
  • Server unavailable
  • Timeout (configurable via LAUNCHER_REQUESTS_TIMEOUT)
UnpackingError:
  • Corrupted download
  • Missing 7z dependency
  • Insufficient disk space
Solutions:
  1. Check internet connection
  2. Verify all dependencies installed
  3. Try again later if servers are busy
  4. Increase timeout: export LAUNCHER_REQUESTS_TIMEOUT=16000
  5. Check download integrity in temp folder

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Update Locations

Temporary files: 
{temp_folder}/
├── updating-{game_id}/          # Game update files
│   ├── .predownloadcomplete     # Predownload marker
│   └── *.zip                     # Downloaded archives
├── updating-{voice_en}/         # English voice pack
├── updating-{voice_ja}/         # Japanese voice pack
└── ...
Game installation: 
{game_path}/
├── .version                      # Current version file
├── GenshinImpact.exe            # Game executable
├── GenshinImpact_Data/          # Game data
└── {game_name}_Data/
    └── StreamingAssets/
        └── Audio/
            └── GeneratedSoundBanks/
                └── Windows/
                    ├── English(US)/  # Voice packs
                    ├── Japanese/
                    └── ...

Voice Packs

Manage voice language packs

Troubleshooting

Common issues and solutions

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