Hey, I decided to put the code I used for doing my lighting solution on github. I couldn't find any readily available assets to achieve this effect so I made them for the jam. It's basically like the lighting from the dark levels in Nuclear Throne.

Here's the github page with the package to import and the instructions on how to use it:

https://github.com/GibsS/unity-mask-lighting

Oh and check out my game if you please :) : Darkness Draws Near