Is there a way to create a 2D lighting system that works by subtracting the opacity/alpha of pixels in a black layer?

I don't really want to use the built-in lighting system >_<

Is this 2D or 3D? With 2D you can use light masks and in 3D you can set a light as negative.

    cybereality
    I'm doing 2D

    Are you saying light mask can be used to achieve a subtraction effect or are you just saying that I should use the built-in lighting system?

      Yes, Light2D can be used for many things. I think it has a blend mode, I will have to check, but I know people have used it for shadows. It is basically just an image that overlays a part of the screen. But you could put what you want in the image (even dynamically) and then blend it in different ways.