Futoshiki is a board-based puzzle game, also known under the name Unequal.
It is playable on a square board having a given fixed size (4x4 for example).

The purpose of the game is to discover the digits hidden inside the board's cells;
each cell is filled with a digit between 1 and the board's size. On each row and
column each digit appears exactly once; therefore, when revealed, the digits of
the board form a so-called Latin square.

At the beginning of the game some digits might be revealed. The board might
also contain some inequalities between the board cells; these inequalities must
be respected and can be used as clues in order to discover the remaining hidden digits.

Each puzzle is guaranteed to have a solution and only one. In order to indicate a move,
click the desired square and select a digit or the delete sign (X); you can also use
the digits on your keyboard (in this case, the digit 0 is equivalent to the delete sign).