Dominosa is a logic puzzle game. You have to find the location of all dominoes on the grid. A domino is a pair of numbers. You can have only one of each pair. Dominoes originated in China before being brought to Europe in the early eighteenth century. Dominosa is a German puzzle, according to Martin Gardner, invented by O.S. Adler in 1874. It was patented by Richard Osa (pseudonym for O.S. Adler) in Germany in 1893 as German Reichs Patent No. 71539 and he published it in 1894 under the name of "Dominosa" combining 'Domino' with his initials. It later appeared in a domino puzzle book in 1912 co-authored by Fritz Jahn.