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Hidato (Hebrew: חידאתו, originating from the Hebrew word Hida = Riddle) is a logic puzzle game invented by Dr. Gyora Benedek, an Israeli mathematician. The goal of Hidato is to fill the grid with consecutive numbers that connect horizontally, vertically, or diagonally. Numbrix puzzles, created by Marilyn Vos Savant, are similar to Hidato except that diagonal moves are not allowed. The names Numbrix and Hidato are registered trademarks.
About the puzzle
In every Hidato puzzle the smallest and the highest number are listed on the grid. All consecutive numbers are adjacent to each other vertically, horizontally, or diagonally. There are more numbers on the board to help to direct the player how to start the solution and to ensure that Hidato has only a single solution. It is usually played on a square grid like Sudoku or Kakuro but it can also include irregular shaped grids like hearts, skulls, and so forth.
Every well-formed Hidato puzzle is supposed to have a unique solution. Moreover, a Hidato puzzle intended for human solvers should have a solution that can be found by (more or less) simple logic. However, there exists very hard Hidato puzzles, even of small size.
As in many logic puzzles, the basic resolution technique consists of analyzing the possibilities for each number of being present in each cell. When a cell can contain only one number (Naked Single) or when a number has only one possible place (Hidden Single), it can be asserted as belonging to the solution. However, as in the Sudoku case, the resolution of harder Hidato or Numbrix puzzles requires the use of more complex techniques - in particular of various types of chain patterns.