Singles
Black out duplicate numbers so every row and column is unique
Black: – · Circled: –
Tap or click a square to use the chosen action; tap again to restore the number. Right-click circles. Arrow keys move; Enter or B blacks out, Space or C circles, Backspace clears. Ctrl or ⌘ Z undoes; Shift Z redoes.
Progress saves on this device.
How to play
Black out squares so that no number appears twice in any row or column. Black squares may not touch side by side, and all white squares must stay connected through their sides; touching corners do not count.
Circle a number you are sure stays white. Two circled copies of one number in a line, touching black squares and cut-off white areas are marked with ! as you play. A square left unmarked counts as white.
Undo and Redo follow your history; a new move after Undo replaces the old branch. Restart returns to the original grid and can be undone. Solve reveals the answer and does not count as solving the puzzle yourself.
Puzzle by Nikoli (Hitori). Engine: Simon Tatham’s Singles, contributed by James Harvey. MIT license and credits.