Transparency notes

On the Sega Genesis and NES the first color for each row is transparent. When you important a png file it can contain transparent data. It is better to use a png file with transparency than a mask color however a mask color will also work if you ensure that it is in color of the palette row. When the same color is in multiple places in the row the last color will be picked. You can take advantage of this if you want the transparent color to be the same as a solid color. In sonic one the sprite of sonic uses black for transparency and solids. This also applies to all sprites that share the same palette with sonic.