So, do you know what this is?
This is the color palette for the original Nintendo Entertainment System. It technically had 64 colors in it, but nine of them are black and there are also two shades of gray that look almost identical to some other colors…So let’s play it safe and say that it had a palette of 54 colors.
The NES had 4-color sprites and one of those colors always had to be transparent. So unless you were using the background to bleed another color through or layered sprites on top of each other, like they did with Mega Man’s face, you were limited to three colors.
An interesting article on the NES and color. Check out his colorful examples.

