The .app structure for Mac OS is a folder. Folder name: “MyGame.app” and then contains the folders/files described in the documentation under deploying for Mac OS target platform.
The MyGame.app folder will not be executable via terminal, because it is just a folder. However, MacOS reads it as an “app” and will execute the “app” per the parameters set in the .app folder config file(s). For example, if your .app folder config is present on your desktop, just double click it to run it (because it is a “*.app” named folder, Mac OS will try to index it for Mac OS app configuration. If it finds it, it will launch it as an app, rather than opening it as a folder).