I see! I got confused because of the sprite palette changing trick to have more than 4 colors, so it only really works for foreground sprites larger than 16x16. Either that or I'm getting NES and Gameboy mixed up. Added a fixed version! No 16x16 tile has more than 4 colors, and the background has a max of13 colors!
Thanks for the heads up!
Cool. You are correct that the GBC can set the palette per tile, unlike the NES.
Not sure if you can do palette per scanline tricks on the NES like you can do on the GBC. (I'm more familiar with the GBC hardware)
And you can use layered sprites to get more colors, but due to sprite count limitations that generally isn't super effective. (But Links Awakening DX uses this for Marin's face on a zero death ending, where it has 3 layers to get all the colors in)
