Single tap to fill, double tap to mark with an X
| Single tap | Fill a square. |
| Double tap | Mark a square with an X as definitely empty. |
This is a nonogram, also sold as Picross or Griddler. The numbers beside each row and column tell you how many squares in that line are filled and in what order, and from those clues alone you deduce the whole grid. Fill the right squares and a picture emerges.
It is one of the purest logic puzzles there is. Nothing is ever guessed: every square can be reasoned out from the numbers if you look hard enough. The difficulty comes from knowing which line to attack next, because the grid unlocks itself once you find the row where the clue leaves only one possibility.
Start with the largest numbers. A clue almost as long as the line itself has very few possible positions, and the squares common to all of them can be filled immediately. That overlap technique is the standard opening move.
Mark the empty squares as well as the filled ones. Xs are not decoration: knowing a square is definitely blank constrains its whole row and column, and most stalled puzzles resolve once you start marking rather than only filling.
Work rows and columns alternately. Every square you resolve in a row gives new information to its column, so switching direction after each deduction keeps the puzzle unfolding.
Never guess. Nonograms are always solvable by pure logic, so if you are stuck, there is a deduction available somewhere you have not looked. A wrong guess corrupts everything built on it.
They list the runs of filled squares in that row or column, in order. A clue of 3 1 means three filled, at least one gap, then one filled.
Never. Every puzzle is solvable by deduction alone.
Marking squares you have proved are empty. It is as useful as filling squares in.
Yes, the puzzle is known by several names including nonogram, Picross and Griddler.
No sign-up, no email, no account. Open the page and Number Puzzle is ready to play straight away, on a phone or a desktop.