Hitori is one of the puzzle game.
The rule is simple.

Hitori is played with a grid of squares or cells, and each cell contains a number.
The objective is to eliminate numbers by filling in the squares such that remaining cells do not contain numbers that appear more than once in either a given row or column.

Filled-in cells cannot be horizontally or vertically adjacent, although they can be diagonally adjacent.
The remaining un-filled cells must form a single component connected horizontally and vertically.