Shiftable block puzzle

A shiftable block puzzle comprising a board defining a bottom wall having a flat top surface, a plurality of blocks of different sizes confined for lateral movement on said flat surface, and a restricted area on said flat top surface for reception thereon of a single primary one of said blocks after shifting movements of secondary ones of said blocks to make way for displacement of said primary block from a predetermined starting position, said primary block having means to permit same to be displaced onto said restricted area, said restricted area provided with a protruding element extending above said flat bottom wall and located to prevent said secondary blocks to enter said restricted area, said means to permit said primary block to be displaced into said restricted area being a slot in a lower surface thereof for reception therein of said protruding element to permit said primary block to be shifted into said restricted area.