Michael Ward wrote:
I was curious what families were being represented by the crests/shields on the cards. I'm pretty sure the green cards with the snake swallowing a man are the Visconti. And I think the yellow cards with the six red balls are the Medici. But I'm not at all sure about the blue cards with the crowned white eagle or the red cards with the crowned white griffin. I assume, respectively, Polish/Germanic and British families.
Does anyone know for sure the family names for all four factions?
The red background with the crowned white griffin is, quite rightly, a characteristic part of almost all the coats of arms of the various branches of the house of Gonzaga:
From the link you can see also the connection with Bohemia lion noted by John: in 1394, emperor Venceslaus I allowed the house of Gonzaga to have this lion in its coat of arms.
As in the game, some Gonzaga branches gained great power over Europe by alliances and weddings, marrying into the family of the emperor of the Holy Roman Empire:
And, yes, the other crests are characteristic parts of (or inspired by) the coats of arms of the houses that you mentioned:
blue player = Este
green player = Visconti
yellow player = Medici