Because this app was created with Processing, not on the Apple App Store, their 'Gatekeeper' currently blocks it.All of this may not be required, but to temporarily open the gate to Symmetron just do the following:
- open Terminal utility
- copy & paste the following code at the prompt:
sudo spctl --master-disable
- press Enter
- close System Preferences (if open)
- open System Preferences
- click on Security & Privacy
- click the padlock in the lower left and enter your system password to unlock the choices
- click Anywhere
- confirm Allow From Anywhere
- Launch Symmetron app by double-clicking on "click here to launch"
- click on the allow-only-authorized-apps to restore security
Thanks for taking these extra steps to install Symmetron!