2d lighting..

I’m making a 2d game and I was wondering how to achieve this lighting circles things:

Could someone explain me how this works and how to make it?
I don’t know how this effect is called so I didn’t succeed finding something on the internet that could help me, except this image.

Thanks in advance

I think you want a node material for this, and blend between 2 maps for each item,

lit and unlit

wow awesome

Watch this video:

Thanks for your replies, I’ll look at it tomorrow because I don’t have time anymore.