@neauoire I assumed there was some relationship with your past work in the Famicom. However, I don't quite understand the layering advantage? Is it faster to do since the bits for each channel are separated?
(I don't have much historic context for .chr formats and the Famicom)
@capital For example in Oquonie, I have the outline and fill for player assets as chr tiles, if I want to make the fill color of the character blink, I can draw only the second half of the chr tile for just repainting the fill, or both at once.