How to create a fog or cloud material for mobile game

Hey guys. I need some kind of fog effect for my mobile game. I’ve tried using the fog sheet from blueprint office example. But it doesn’t render on the mobile preview. As I very little knowledge about materials, so I don’t know what can I change to make it work on mobile.

I’ve also tried using the cloud particles from the Landscape Mountain demo, but it is extremely large and it disappears when the camera goes closer.

I would really love getting a few ideas from you guys on how can achieve it or cheat it.

As far as performance is concerned what will be more efficient, Particle or Plane with transparent material?