Hello. It works fine on my MacOS Catalina. The problem is that the latest versions of MacOS mark the launcher of unknown binaries as non-executable file. After you extract the .zip file, right-click on the .app file > show package contents, then open a terminal inside its Contents/MacOS folder. Then, type chmod +x Pixelorama . Go back to the .app file and you can now open it normally.
Hello there, thanks for commenting. Unfortunately, Godot (the engine Pixelorama is made in) does not allow exporting in .dmg format if you're using Windows or Linux. In order to export to .dmg, we would need to do it from a Mac, which we currently don't have.
There's not much we can do right now about it since we don't own a Mac machine, but we'll update the install instructions based on what @rafaelgdp said!