The dev didn't make the actual app itself an executable file. To fix, this will require some knowledge of Terminal.
1. Open Terminal
2. Enter this command:
cd /Applications/Nobody\'s\ Home.app/Contents/MacOS
Note: The path here may differ if you put the "Nobody's Home" app elsewhere on your hard drive
3. Enter this command:
chmod +x nwjs
4. Close Terminal
5. From Finder, double-click the app
6. If you get anything telling you the app won't open because it's from an unverified developer, open System Preferences, go to "Security & Privacy," click the "General" tab, and click "Open Anyway" at the bottom of the window.
7. Try opening the app again.
Note: For me, the app crashed on startup due to a fatal error. Here's to hoping you have better luck.