How to play

Each number beside a row or above a column tells you how many squares in a row are filled in that line, and a line with several numbers has several separate runs, in that order, with at least one empty square between them. A clue of 3 1 means a run of three filled squares, a gap, then one filled square. Fill the grid so that every row and every column matches its numbers. When a line is complete, its clue is greyed out.

Click or tap a square to fill it, and drag to fill several at once. Switch to Cross out to mark squares you are sure are empty; crosses are only a reminder and don’t count in the answer. With a keyboard, click the board, move with the arrow keys, press space to fill and X to cross. Check highlights filled squares that are wrong, and Clear starts the same picture again.

Sizes and fairness

Choose 5 × 5 to learn, 10 × 10 for a real puzzle, or 15 × 15 for a long one. Each picture is a random pattern, and the game only keeps patterns that can be solved by reasoning one line at a time, so you never need to guess. The 15 × 15 board has small squares, so it plays best on a larger screen. Your best time for each size is saved on this device.

Tips

Start with the biggest clues. In a line of 10 with a clue of 8, at least six squares in the middle must be filled whichever way the run sits. Add the numbers and the gaps between them: if they use up almost the whole line, there is little room to move and many squares are certain. Work back and forth between rows and columns, and cross out squares as soon as a line is complete.