In 1974, a Hungarian professor of architecture named Ernő Rubik cobbled together a cube made from wood and paper ... a patent to market his invention, a puzzle game that eventually became ...

The Puzzle of Us All, equal parts memoir and philosophical insights, Rubik describes the room in which he prepared for his classes as 'a child’s pocket, full of marbles and treasures', including ...

That's not counting the sales of other types of puzzle cubes by different brands. Some are wooden, others electronic with built-in bluetooth, then there are those with all manner of colourful designs.