Fast Stylized Shadows

Fast Stylized Shadows is exactly what it says on the tin, a very efficient implementation to add a bit of style to your shadows.
Works great on mobile and can give low resolution shadows a bit of extra flare to disguise the low resolution with minimal artifacting.
Fully customizable via an input style texture and a few parameters.
Can do things like give shadows a dithered or grainy look, or even a sort of brush stroke or stippling effect. It's up to you!
NOTE: Requires using screen-space shadows by default, code could be used to modify existing shadow sampling implementations though. And on this note, because of this it only works for realtime shadows and not baked shadows or spotlight cookie type shadows etc.
NOTE V2: Because this uses a custom screen-space shadows shader, if you're already using one of those you'll need to modify the existing one slightly.