Except Universal apps are entirely new for Windows 10 -- so it's an empty and new platform that sits alongside regular Windows applications. Developers have to

Except Universal apps are entirely new for Windows 10 -- so it's an empty and new platform that sits alongside regular Windows applications. Developers have to go out of their way to develop for this separate platform in a platform and, from what I've seen, they aren't. I'm still running Windows 8.1 on my devices so I can't even run these universal apps.