Yu-gi-oh! OriCas (or Original Cards) are custom cards inspired by many factors like the anime series, or redesigns of original cards
These cards cannot be used in any official duel, or tournament except for cards that summons tokens like "Scapegoat" but they are NOT required
The redesigned cards of the original TCG are called "Proxy OriCas"
Here is an example of a "Dark Magician Girl" Orica copied from the anime
And here is an example of a very malicious "Dark Magician Girl" custom made