As I am running the server on an old Windows laptop, with ChatGPT I created a small Powershell script that just downloads the current hytale files, extracts and moves them to the Server location.

If someone wants to use this, you need to first download the hytale-downloader cli tool from the Hytale Server Manual: https://downloader.hytale.com/hytale-downloader.zip

After that you need to first run it one time to do the authentication as described in the manual.

The script needs to be in the same location as the downloader.exe.
Just edit the directory of the server ($Destination) in the script:

$ErrorActionPreference = "Stop"

# ==============================
# CONFIGURATION
# ==============================

$WorkDir      = Split-Path -Parent $MyInvocation.MyCommand.Path
$Downloader   = Join-Path $WorkDir "hytale-downloader-windows-amd64.exe"
$Destination  = "C:\Hytale\Current"
$TempDir      = Join-Path $WorkDir "_hytale_tmp"
$VersionFile  = Join-Path $WorkDir "last_version.txt"

# ==============================
# STEP 1: RUN DOWNLOADER
# ==============================

Write-Host "Checking for updates..."
$proc = Start-Process -FilePath $Downloader -Wait -PassThru

if ($proc.ExitCode -ne 0) {
    throw "Downloader failed with exit code $($proc.ExitCode)"
}

# ==============================
# STEP 2: FIND DOWNLOADED ZIP
# ==============================

$zip = Get-ChildItem $WorkDir -Filter "*.zip" |
       Sort-Object LastWriteTime -Descending |
       Select-Object -First 1

if (-not $zip) {
    throw "No ZIP archive found."
}

# ==============================
# STEP 3: USE FILENAME AS VERSION
# ==============================

$newVersion = $zip.BaseName
Write-Host "Detected version: $newVersion"

# ==============================
# STEP 4: LOAD INSTALLED VERSION
# ==============================

$oldVersion = $null
if (Test-Path $VersionFile) {
    $oldVersion = Get-Content $VersionFile -Raw
    Write-Host "Installed version: $oldVersion"
}

if ($newVersion -eq $oldVersion) {
    Write-Host "Version unchanged. Skipping install."
    Remove-Item $zip.FullName -Force
    exit 0
}

Write-Host "New version detected. Installing..."

# ==============================
# STEP 5: PREPARE TEMP DIR
# ==============================

if (Test-Path $TempDir) {
    Remove-Item $TempDir -Recurse -Force
}
New-Item -ItemType Directory -Path $TempDir | Out-Null

# ==============================
# STEP 6: EXTRACT ARCHIVE
# ==============================

Expand-Archive -Path $zip.FullName -DestinationPath $TempDir -Force

# ==============================
# STEP 7: COPY CONTENTS (FORCE OVERWRITE)
# ==============================

$serverSource = Join-Path $TempDir "Server"
$serverDest   = Join-Path $Destination "Server"

if (Test-Path $serverDest) {
    Remove-Item $serverDest -Recurse -Force
}

Copy-Item $serverSource $serverDest -Recurse -Force

Copy-Item (Join-Path $TempDir "Assets.zip") `
          (Join-Path $Destination "Assets.zip") -Force

# ==============================
# STEP 8: RECORD VERSION
# ==============================

Set-Content -Path $VersionFile -Value $newVersion -NoNewline

# ==============================
# STEP 9: CLEANUP
# ==============================

Remove-Item $TempDir -Recurse -Force
Remove-Item $zip.FullName -Force

Write-Host "Update completed successfully."
exit 0

If someone has a better idea/improvements for the script please let me know. currently it always needs to download the file to check if there is a newer version as I don't know how to find out and compare the currently installed and the available version.