Last time I got pretty deep in, but it became impossible when the chess notation rule required Cs and Ds, making it impossible to stay below the roman numberal sum limit.

I got past it because it happened to throw a place from my country. And there was also a flagpole with a flag on it to really drive it home. XD

I used Google lens. Got stuck afterwards on a chess rule. The captcha rule used the notation for the chess one to complicate it further haha