Actually, I am not 100% sure. But if my light is bound between 0 and 1, and my shadow is actually made by black tile but use code to make it transparent is it another way of controlling analog and transparency? Because all my assets are fully black and white:
*Transparency should be implemented at the engine/code level.
You can not use alpha in your art files, but you are allowed to change the alpha when the game is running to create effects like fades, trails and ghosts.