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How to Run the G4 Launcher on macOS (Unsigned App)

The G4 Launcher is ad-hoc signed but not notarised by Apple. macOS Gatekeeper will block it the first time you run it. The steps below let you open it — no system settings need to stay changed permanently.

What you'll see

When you double-click the launcher, macOS shows:

"G4Launcher-macos cannot be opened because Apple cannot check it for malicious software."

or

"G4Launcher-macos is damaged and can't be opened."

The "damaged" message is macOS quarantine in action, not a corrupt file. Both are resolved the same way.

Method 1 — Remove the quarantine flag (recommended)

macOS marks every file downloaded from the internet with a quarantine attribute. Removing it is the cleanest fix and takes one Terminal command.

  1. Open Terminal (Applications → Utilities → Terminal, or press ⌘Space and type "Terminal").
  2. Run the command below — replace the path if you saved the file elsewhere:
xattr -d com.apple.quarantine ~/Downloads/G4Launcher-macos
  1. Make the file executable if it isn't already:
chmod +x ~/Downloads/G4Launcher-macos
  1. Double-click the file or run it from Terminal:
~/Downloads/G4Launcher-macos

The launcher opens. You won't need to repeat this for the same file.

Method 2 — Right-click open

If you'd rather not use Terminal:

  1. Right-click (or Control-click) the launcher file.
  2. Choose Open from the context menu.
  3. A dialog appears with an Open button — click it.

This only works on the first run; after that the file opens normally with a double-click.

Verify the file before running

Open Terminal and run:

shasum -a 256 ~/Downloads/G4Launcher-macos

Compare the output to the SHA-256 shown on the download page. They must match exactly before you open it.

"Operation not permitted" error

If the xattr command fails with a permissions error, prefix it with sudo:

sudo xattr -d com.apple.quarantine ~/Downloads/G4Launcher-macos

Enter your Mac password when prompted.

Why isn't it notarised?

Apple notarisation requires an Apple Developer Programme membership (£79/year) and a Hardened Runtime build. We plan to add this in a future release. The SHA-256 checksum on the download page lets you verify the file's integrity independently in the meantime.