The illustration is a detail from Brueghel's painting, "Children's Games", done in 1560. The rules below are taken from Traditional Games of England, Scotland and Ireland by Alice Gomme.
From Gomme: "One boy is chosen as Cock. He is blindfolded, and stands alone, with his legs as far apart as possible. The other boys then throw their caps as far as they are able between the extended legs of the Cock. After the boys have thrown their caps, and each boy has taken his stand beside his cap, the Cock still blindfolded, stoops down and crawls in search of the caps. The boy whose cap he first finds has to run about twenty yards under the buffeting of the other boys, the blows being directed chiefly to the head. He becomes Cock at the next turn of the game."
Gomme, Alice - Traditional Games of England, Scotland and Ireland (London, Thames and Hudson, 1894, 2 vol. ISBN 0-500-27316-2)
Portman, Paul - Pieter Brueghel's Children's Games (Berne, Hallwag, 1964)