No Terminal stuff required in Sequoia, FYI!
You just have to:
- Change your Security setting "Show Applications From" to "App Store & Known Developers".
- Try launching the Ghost Town application you downloaded. (You'll get that deeply insulting pop-up about how Apple is protecting you from, um, software).
- Go back to your Security settings (in System Preferences), and scroll to the bottom. You'll see an option to run the ghostly app the OS just blocked.
It should run, and you should just be able to double-click the application in the future.
Is it dumb and hostile? You betcha! But not too time-consuming.