Game consoles of old use palettised sprites, a range of colour indexes that could be swapped out to make sprites different colours. The most famous example of this is in super mario bros on the NES, where with a simple swap of the palette, bushes can be clouds. It's a deep topic with many technical details, that is common to 8-bit and 16-bit machines. On modern computers however, this technique is not really an option in the way it was on those consoles. Now we have to rely on remapping luminance in textures on the graphics card using shaders.

Often this is done with tinting, taking a grayscale image and tinting it wholly so all of the texture is a desired shade like green or red. Is this possible for sprites that have 16 colours? Can we address certain colour indexes and swap them out, and why would we want to do that anyway?

In the image above, there are 3 layers: torso, legs and hat. When put together, they make a cowboy. Applying a shader that remaps the grayscale to set colours, gives way to many types of cowboy using one sprite. With a little bit of planning, it's possible to make details like badges, bandanas, waistcoats etc. appear by swapping colour palettes alone.