How to make volumetric fog for my mobile game?

I want to create fog or mist like in this game ‘Sky Dancer Run - Running Game’ and also i need horizontal movement like in this game with Character Controller i have in my game.

You can create fog in unity itself, but the best way is to use a plug - in from the asset store, like Weather Maker - 2D & 3D Sky System for Unity, for instance, (theres plug-ins for both desktop and IOS) far better options, functionality and control.