The permissions on the executable were not set correctly when uploaded to itch. You can fix this by opening Terminal, go to the MacOS directory within the app, and giving it the execution permission. For example:
- Launch Terminal
- type “cd ~/Downloads/TheSignalMac/TheSignalMac.app/Contents/MacOS”
- run the command “chmod +x The\ Signal”
- Then hold Alt when right-clicking to launch the app the first time.
To the author: I use butler to upload to itch. The “–fix-permissions” option works for me. For instance: “butler push –fix-permissions TheSignalMac.app oddball/the-signal:macos”