The original 26 maps are 256x256 tiles. The BONUS maps are smaller, to keep the proportions of the land masses closer to the cartographic reality (mercator projection). Of course I could try to make a few 256x256 maps that cover all of earth from north to south, as you propose in your other post. This might lead to a disproportional representation of the oceans, since they are vast, "empty"-looking water masses...