Open source implementation of Microsoft's .NET Framework
To manually install Mono with Homebrew, use the following command:
Current version of #: 6.12.0.206
ARM: https://download.mono-project.com/archive/6.12.0/macos-10-universal/MonoFramework-MDK-6.12.0.206.macos10.xamarin.universal.pkg
Intel: https://download.mono-project.com/archive/6.12.0/macos-10-universal/MonoFramework-MDK-6.12.0.206.macos10.xamarin.universal.pkg
Website: https://www.mono-project.com/