How to play 15 Puzzle
Arrange fifteen numbered tiles in a 4 × 4 square. The empty space is your only room to move, so plan a route that brings each number into position.
- Move a tile horizontally or vertically into the adjacent empty space. Diagonal and non-adjacent moves are not allowed.
- Put 1–15 in row order, leaving the empty space in the bottom-right corner.
- New free-play boards are scrambled by legal moves from a solved board, so they can be solved.
Controls
- Tap or click a tile next to the empty space.
- Arrow keys move the empty space: the neighbouring tile slides in the opposite direction.
- Undo reverses your last move. Hint previews a checked move; choose Apply this move or move the tile yourself.
Three fixed levels and generated free-play boards are available. Hint uses a bounded search. A recorded-route fallback is clearly labelled and may undo your last move.
Progress is saved in this browser on this site when storage is available. Clearing site data can remove it. There is no cross-device sync, and internet access is needed to load the game.
Frequently asked questions
Which tiles can I move?
Only a tile directly above, below, left or right of the empty space can move into it. Diagonal tiles and tiles farther away cannot move.
Which way do the arrow keys move?
Arrow keys move the empty space in the key’s direction. The neighbouring tile moves the opposite way into the old gap. A key pointing beyond the board does not move a tile.
Does Hint find the shortest solution?
Hint checks a complete route from the current board within a search budget, then previews one move without changing the board. It does not promise the fastest or shortest solution for every random position. If the budget is reached, a verified recorded route may be offered with a warning that it may undo your last move and take extra moves.