Slide Fifteen is the sliding tile puzzle that many of us remember from a toy shelf. The numbered tiles are jumbled, there is one gap, and you slide the tiles around until they are in order again.

How to play

The goal is to put the numbered tiles in order, with 1 first and the gap in the bottom right corner. On the 4 by 4 board the order reads 1 to 15 across each row.

Sliding: tap a tile that is in the same row or column as the gap. It slides into the gap. If other tiles are between it and the gap, they all slide along together.
Counting: every tile that slides counts as one move. Sliding three tiles at once counts as three moves.
Leaf marks: a tile that already stands in its right place shows a small leaf, so you can see your progress at a glance.
Winning: when every tile is in place, you win.

On a computer, you can use the arrow keys instead of the mouse. An arrow moves the tile on the opposite side of the gap toward it. For example, the Left arrow slides the tile on the right side of the gap into it. Undo takes a move back, and Restart returns to the starting jumble.

Every board here can be solved. The tiles are mixed by a method that guarantees a solution, so you never face a board that looks fine but cannot be finished.

The levels

The levels change the size of the board and how far it was scrambled. The boards were chosen by the fewest moves a perfect player would need.

Easy: a small 3 by 3 board with eight tiles. The best solution takes between 10 and 20 moves.
Medium: the classic 4 by 4 board, shuffled a fair amount. The best solution takes between 22 and 32 moves.
Hard: 4 by 4 again, but shuffled far. It takes at least 40 moves, even for a perfect player.
Expert: a big 5 by 5 board with 24 tiles.

There is no Hint button in this game. Undo is your safety net.

Today's game

The daily game is a Medium board. Everyone who plays on the same calendar day gets the same jumble, so you can compare your moves and your time.

Tips

Solve the top row first. Place the 1 and 2, then the 3 and 4, and leave them alone.
The last tile of a row is the tricky one. You may have to move a finished tile out of the way for a moment and then put it back.
Then solve the left column, and keep working inward. Each row or column you finish makes the puzzle smaller.
Leave the last two rows for the end. They need a different way of working, one column at a time.
Do not be afraid to undo a set of moves that went wrong. It is quicker than trying to repair the mess.
Slide several tiles at once when you can. It saves a lot of tapping, even though every sliding tile adds to your count.
On the 5 by 5 board, take your time and tidy one row after another. The same method works at every size.

A bit of history

The sliding tile puzzle was a worldwide craze in the late 1800s, and it has been a favorite for generations since.

Questions

Can every board be solved? Yes. A board is only used when it passes a check that proves it can be solved.

Why does a tile far from the gap move? Any tile in the same row or column as the gap can slide. The tiles between it and the gap move along with it.

What is the fewest moves number? It is the best possible solution for that board. You can finish with more moves, which is normal.

Is there a way to see a hint? No. Use Undo to try different ideas without any penalty.

Slide Fifteen Puzzle