Hi,
A couple of threads back I brought up the possibility that domino cards might have preceded the Mamluk deck in Europe. Here is a bit of Tarot lore from The Sorcerer and His Apprentice by R. A. Gilbert, which is really a collection of writings from MacGregor Mathers and JBrodie-Innes. Mathers is describing card history information that he got from a Mrs. Lee, a gypsy fortune teller. "Curiously enough the numbers akin to the Pythagorean system of numbers, especially in regard to the occult meaning of odd and even numbers. Mrs. Lee laid particuar stress on the arrangement of the pips on the cards, pointing out its similarity to the arrangement of spots on dice and dominoes. ( The connection to this with the Pythagorean system is obvious).
The picture of the men playing cards does to me look like they are playing with "dot" cards, not the decorative Mamluk deck. If domino cards entered Europe during the Mongolian peace when Europeans were in contact with that card playing society; they might have developed a system of card play based on Pythagoras/Timaeus (plato). This "dot" card philosophy could have been tranferred onto the Mamluk cards when they came in.
For the story of the cultural exchange between Mongolians and Europeans I refer to the book by Jack Weatherford, "Genghis Khan and the Making of the Modern World." He describes the Mongol world war that lasted from 1211 to 1261, and ushered into being a new global culture.
"Although never ruled by the Mongols, in many ways Europe gained the most from their world system. The Europeans received all the benefits of trade, technology transfer, and the Global Awakening without paying the cost of conquest...One technological innovation after another arrived in Europe....The replacement of parchment by paper, a Chinese innovation already known but only rarely used in Europe prior to the Mongol era.."
But on the other hand, in favor of the Mamluk theory... Apparently the word hazard as in Games of Hazard or chance as compared to games of skill is an Arabic word. "Zahr" is the Arabic name for dice, and the implication here is that games of hazard are gambling games. So much for the Islamic taboo on gambling. (Cardano: The Gambling Scholar)
But I agree we have no where to go with this as we are stuck in a speculative mode. I do recommend Cardano's book, "the Book on Games of Chance." Cardano lived from 1501 to 1576, and his book on games gives a inside view of gaming during that time. He sees gambling as therapeutic during times of stress and grief. He also describes how "marked cards" worked as codes. I agree that card play is very therapeutic. I also find card divination therapeutic, and in fact use it most under stress.
But back to the "dot decks." I've got out my magnifying glass and I am looking at "Men Playing Cards" and it looks to me as if the one card raised in front has two dots on it and it isn't the backside decoration because the other players are holding up cards with the backside visible and they are blank. On the table it appears that there is a card that looks like four dots. Also, in the center of the table there is an object that looks like a dice.
Possibly the French suit signs (which came into being in the 1480s) were a combination of the hypothetical "dot" deck with the Mamluk suits--cups/hearts, spades/swords, clubs/clubs, and diamonds/coins.
Good luck in your research...