Colouring rules:
1. The base can be any natural horse colour (bays, chestnuts, champagnes, roans, etc.)
2. They can have all of the paint/appaloosa/pintaloosa markings of a normal horse.
3. They can have any of the white markings and more unusual markings (bend-or spots, birdcatcher spots, etc.) on their coat.
4. Somatic mutations (chimeras/mosaics) are, like with real horses, extremely rare
5. All horses have striped brindling, known as 'Atgili' (a word derived from combining the Turkish words 'at' (horse') and 'çizgili' (stripes):
> Lighter-coloured horses will have darker Atgili, so a cremello horse will have dark brown Atgili
> Darker-coloured horses will have lighter Atgili, so a blue roan horse will have pale grey/white Atgili
6. Atgili always occur on the neck, torso and the upper legs. They cannot be found anywhere else on the body.
7. Atgili can be any length and any width, with some stretching all over the main body, while some merely stripe the legs. Some Atgili are mottled, but most are straight, wavy brindling lines.
8. On some very rare occasions, horses without Atgili are born. These horses are often sought after by royalty due to how unusual they are!
***Might add more later. ^^