This translation makes perfect sense, so we are looking at the kind of game described by Huck.Ross G. R. Caldwell wrote:For "zurlo" the Zingarelli says "a variant of ciurlo, attested by 1449". They say it means "Ruzzo" (Tuscan).
Ruzzo seems to mean "whim, fancy, or caprice".
http://en.wiktionary.org/wiki/ruzzo
Ciurlare means to sway or totter -
http://en.wiktionary.org/wiki/ciurlare#Italian
It seems to refer to the behavior of the "ball" (looks like a cheese roll here), which would roll or totter one way or the other in a capricious fashion.
So maybe "Be careful of the (roll of the) Zurlo, that it doesn't knock down the Matto, because then the turn is null."
Edited to add -
Ottavia Niccoli, in "People and Prophecy in Renaissance Italy", without going into the etymology of zurlo, translates it as (p. 26) -
"Take care that the zurlo does not strike down the Mato, because if it does the match is off."
Interestingly, the "ball" is not a ball.
This reminds me of the "Game of the sphere" (De Ludo Globi) by Nicolaus Cusanus:
http://books.google.com/books?hl=it&id= ... id&f=false
Also in that case, the game was based on a "ball" with an irregular shape. And also in that case the strange movements of the ball were interpreted as a metaphor of the world.
Such wild movements will certainly require some "fortune" in order to win the game. I think that the image intentionally recalls a wheel of fortune, as proposed by Robert.
The cities that are still standing with Venice could be:
Vicenza, Padova, Treviso.
The trees can indeed refer to the Pope, France and Spain, as suggested by Huck. But what is the meaning of the banners?
Marco