The grid is five by five and hides a pattern of filled squares. The numbers along the top and down the left give the length of each run of filled squares in that column or row, in order, separated by at least one gap. A zero means the line is empty. Fill in every square of the hidden pattern and the puzzle reports itself solved.
There are no points, no move counter and no timer. The only outcome is the solved message, which appears as soon as every square of the hidden pattern is filled and no extra square is. Crosses are your own bookkeeping and are never checked, so you can use as many or as few as you like. The check runs after every fill, so the message appears the instant the last correct square goes in.
Patterns are generated at random, so a clue set can occasionally fit more than one arrangement and only the generated one is accepted. Press New Puzzle.
No. They are only a note to yourself. The check looks at filled squares alone.
Yes. On a touch screen the game shows on-screen buttons, and games played with a mouse work by tapping.