Real time shading soft shadows

I recently faced a challenge where I had to light real time characters in standalone VR. On those hardware there is no real time lighting as on PC, no GI, no soft shadows, but I wanted to render dark and foggy scenes for the movie I was responsible of. So I decided to develop my very own lighting pipeline. To avoid the use of hard shadows with one directional light, or worst, no shadow at all, I had to think out of the box and redefine how shadows are drawn. I imagined a shader solution to have more flexibility, more detailed and with more control, in real time at 60 fps on VR standalone headset.