Originally manufactured by Kum-Bak Sports, Toys & Games London, circa 1935;
this puzzle a 1961 Adams Co. Dad's Puzzle,
with cardboard sleeve by J. A. Storer 2007.
(cardboard sleeve, metal tray, and 9 plastic pieces, 3.75 x 3 x 5/16 inches,
the sleeve has directions for Nine Block, Dad's Puzzler, Quzzle, and Quzzle Killer)
The same piece set as
this name is sometimes used to refer to Dad's Puzzler (e.g., in the Filipiak book).
It is presented on the web page of Hirofumi Fujiwara as puzzle 17 of his "Step By Step Problems",
and also in the Hordern book.
The start position is different from Dad's Puzzler, but the problem is the same;
slide the 2x2 piece from the upper left to the lower left
(without picking up pieces):
A Nine Block Solution
Here is a solution of 47 straight-line steps;
it can be converted to 45 rectilinear moves by combining steps 6/7, 36/37:
(one move = sliding one piece any number of units in one direction)
Nine Block Diagonal
Dad's Puzzler Diagonal,
it is natural to consider moving the 2x2 piece to the lower right corner than the lower left:
the diagonal version of Nine Block is an easier problem.
Here is a solution of only 29 straight-line moves that can be converted to 27 rectilinear moves by combining steps 6/7 and 18/19: