Yenboo Futoshiki (不等式, futōshiki?) is an extended version of the Japanese logic puzzle game named 'Futishiki'.
Futoshiki means inequality. It is also spelled as 'hutosiki'. The puzzle is played on a square grid, such as 5 x 5. The objective is to place the numbers 1 to 5 (or whatever the dimensions are) such that each row, and column contains each of the digits 1 to 5. Some digits may be given at the start. In addition, inequality constraints are also initially specifed between some of the squares, such that one must be higher or lower than its neighbour. These constraints must be honoured as the grid is filled out. Clicking the numbers at the bottom of the screen and selecting any cell on the game board will assign the selected value to the game board. The gamer will be successfull, as all the empty cells are correctly filled out without using the same number twice on each row and column.