Indeed, skins are a collection of modified text- or image files bundled into another zip-file that replace the original look when applied. Skins are useful when you don’t want to touch the original map-files and/or maybe want to offer a variety of changes to the public.
But you don’t need to apply a complete skin when you want to change the look of your map.
For example in the Global 40 map.properties file the territory colors of the map are defined like this:
color.Neutral=d8ba7c
color.Neutral_True=b88a6c
color.Neutral_Axis=6A5B3D
color.Neutral_Allies=d8ba7c
color.Italians=58360E
color.British=916400
color.UK_Europe=916400
color.UK_Pacific=8E6600
color.French=156CC4
color.Impassable=d8ba7c
color.Americans=5a5a00
color.Russians=af2828
color.Germans=5a5a5a
color.Japanese=DCB53F
color.Chinese=713778
color.Canada=bf0010
color.ANZAC=4d7f7f
color.Dutch=ff6d00
color.Mongolians=d8ba7c
Now adjust the (hex RGB) color code to your needs. Save the file and play…