Kuromasu puzzle rules

Each number counts the light cells it can see in its row and column, including itself. Dark cells stop the view.

One rule at a time

1. Numbered cells stay light. Count the number itself, then look along its row and column until a dark cell or the frame stops you.
2. Dark cells cannot share an edge. They may touch at a corner.
3. All light cells must belong to one group connected through edges. Decide every empty cell to finish.

A useful first deduction

A corner clue of 5 on a 3 × 3 grid sees its own cell plus two cells to the right and two below. Those four cells must stay light.

Mark a board

Tap to cycle dark → light → clear. Arrow keys move; D marks dark, L marks light, Backspace clears.

Use the buttons below the board to mark its selected cell or connection. Undo removes your last move. Restart clears only the board you are playing, after confirmation.

When a board is finished

Fill all cells. The game checks the clues, forbidden patterns and connected areas. A conflict message points out a rule that cannot be satisfied. Completing the board opens the next puzzle action.

Hints and daily puzzles

A hint points to one forced move and explains the deduction. Apply it only when you are ready. If your marks leave no valid completion, undo an uncertain move first. Daily boards use a separate original set and stay fixed for the UTC day. Return to a past saved daily board until you choose today’s board.

Nikoli · Kurodoko rules. PuzzHive’s boards, interface and artwork are original; no puzzle from this reference is reproduced.