How can I achieve homogenous lighting? (Same intensity no matter the range from origin)

So I'm making a top down view game with a sphere rolling through a completely dark maze while illuminating the environment. So currently, I've set a point light as a child of the sphere. However, I want to achieve a certain effect: I want light intensity and color mixing to be equally intense no matter how far away from the light source it is. I want to achieve something along the lines of the bottom half of the diagram I drew:

• If a surface cannot be seen by any light source, it will be completely black.

• If a surface can be seen by a certain light source, it will be colored a constant color.

• If a surface can be seen by two light sources, their colors combine with a constant color.

• The distance between light source and surface affects nothing

I'll guess this could either be done by modifying Light, using a special Material or applying a certain Shader. So how could I achieve this effect?