I am happy to hear that you enjoyed the game.
Sadly I don't think I can help you with your problem because I use Godot for my games and my experience with Unity is almost none
Yes, something similar to the light mechanic in your game. I'm also interested in learning how to create the masking effect where you can always see the floor and other static items in the level but you can see the enemies or some specific items only when they are in direct line of sight.
I followed this tutorial but the masking effect was glitchy when I tried it in Unity.
https://yewtu.be/watch?v=CSeUMTaNFYk
Anyway, I'll checkout Godot lighting meanwhile. If you know where I can learn about this above mentioned masking in Godot, let me know. Cheers!
PS: When are you releasing Deadly Shadows full game? You should definitely expand the game!