Finally uploaded this old fog of war test project from https://unitycoder.com/blog/2014/10/16/2d-fog-of-war-unity/
Its raycast + vertex color based effect. (not really optimized, as it linecasts each vertex right now..)
Sources:
https://github.com/unitycoder/FogOfWar
Cleaning up the project and upgrading from 4.x: