How to play the 15 Puzzle

The 15 Puzzle is the original pocket brain-teaser — a small frame holding fifteen numbered tiles and one empty space. Because there's a single gap, the only thing you can ever do is slide a neighbouring tile into it. From that one simple move comes a puzzle that has fascinated players for well over a century.

Goal

Arrange the tiles in order, 1 through 15, reading left to right and top to bottom, with the empty space resting in the bottom-right corner. The board is shuffled into a position that is always solvable, so a tidy solution is guaranteed to exist — finding it is the fun.

Controls

• Tap or click any tile sitting directly beside the gap to slide it across.
• Desktop: the arrow keys or W, A, S, D slide a tile into the gap from that direction.
• Mobile: swipe across the board to push tiles toward the empty space.

Strategy

Don't try to solve everything at once. Work in layers: place the top row first (1, 2, 3, 4), then the leftmost column below it, locking each finished section away as you go. That shrinks the puzzle to a smaller grid each time. The trickiest moments are the corners — when two tiles need to swap into a tight spot, set them up using the well-known "rotate" trick: park the first tile one position early, slide the second in beside it, then cycle them both into place together.

Tips

• Solve the last two tiles of any row as a pair, not one at a time, so you never have to disturb what's already done.
• The final bottom 2×3 region takes the most practice; think of it as positioning tiles in a loop rather than in strict number order.
• If you tangle the board, keep sliding — every position remains solvable, and a calm reset of one corner usually untangles the rest.
• Count your slides if you like a challenge: experienced solvers can clear a shuffle in well under a hundred moves, and tightening that number is a goal in itself.