Mosaic

What is Mosaic?

Mosaic is a logic puzzle that hides a picture. Some squares of the grid hold a number from 0 to 9. A number says how many of the nine squares of its block are filled: its own square and the eight squares around it (fewer at an edge or in a corner). You fill squares and mark others empty until every number is right, and the filled squares draw a picture. When the last square is in place, the picture comes out in coloured ceramic tiles, like a real mosaic.

Every board has exactly one answer, and it can always be reached by reasoning, never by guessing. There are more than sixty hand-drawn pictures, from a heart and a fir tree to a lighthouse and a steam train, on three board sizes: 10 by 10, 15 by 15 and 20 by 15. A new board, the same for everyone, arrives every day.

How to play

• Tap a square to fill it, tap it again to mark it empty, and once more to clear it.
• Fill or Empty. The first button picks what a tap does first. With Empty picked, a tap marks a square empty, and a second tap fills it.
• Drag along a row or a column to give every square you cross the same state as the first one. A drag only changes squares that were in the same state as the square it started on, so it never wipes out your other work.
• Grey and red numbers. A number turns grey once its block holds exactly that many filled squares, and red once it can no longer come right: too many filled squares, or too few open ones left.
• Zoom. On the bigger boards, pinch with two fingers or tap + to zoom, and move the board with two fingers. Tap the button again to see the whole board.
• Undo takes back your last move, a whole drag at once.
• Score. Your score is the time to finish the picture, plus 15 seconds for every hint. Every board size has its own leaderboard.

Strategy tips

1. Start with 0 and 9. A 0 leaves its whole block empty and a 9 fills it. A 6 on an edge or a 4 in a corner, which see only six or four squares, fill everything they see too.
2. Mark the empty squares. Marking costs nothing, and a mark is what lets the next number tell that it needs every square still open.
3. Count what is left. For any number, take away the filled squares around it: what remains must come from the open squares. When that is all of them, fill them; when it is none, mark them.
4. Compare neighbours. Two numbers side by side share six squares. If a 3 needs all of its filled squares in the part it shares with a 5, then the 5 needs two more in the squares only it sees.
5. Watch the edges. A number by the border sees fewer squares, so it is usually forced sooner than one in the middle.

FAQ

Is Mosaic free to play?

Yes. Like every game on Play, it runs free in your browser, with no download and no account needed.

Does a number count its own square?

Yes. A number counts the filled squares in the block of nine around and including its own square, so a square with a number can be filled too.

Do I have to mark the empty squares?

No. The board is finished as soon as the filled squares match the picture. Marks are there to help you reason: a mark is how a number next to it can tell which squares are still open.

What does a hint do?

It first puts right a square you got wrong, if there is one. Otherwise it fills (or marks) the next square that follows by logic, rings the number or the two numbers that decide it, and the line under the board says why. Each hint adds 15 seconds to your time.

What is today's mosaic?

Every day everyone plays the same medium 15 by 15 board, so times compare directly on the leaderboard.