itch.io

8 layers are needed only for a high-quality gradient transition. 
The conversion script doesn't care how much has been done. 
You can simply skip 4 layers of diagonals or, conversely, draw only diagonal light. 
Or even display the light from only one side on one display.

You need to draw everything manually on each side, on each frame, to get the correct feature normal map for pixel graphics. The color saturation level affects how much the pixel is rotated, in other words, it works from the alpha channel. If you want to make a detailed map of the object's normals, then I advise you to set it to 20-40% transparency.