Hitori (from Japanese "Hitori ni shite kure"; literally "Leave me alone") is a type of logic puzzle.
Hitori is played on a grid of squares. At the beginning, each square contains a number. The goal is to color some cells so that there are no duplicate numbers in any row or column, similar to the solved state of a Sudoku puzzle.
Orthogonal connections are also important. Crossed out (black) cells must not be orthogonally connected, all other cells must be orthogonally connected in a single group. That is, no two black squares may be adjacent, and all squares that are not crossed out must be connected horizontally or vertically to form a single shape.