15-Puzzle
Slide tiles to arrange numbers 1-15 in order.
How the Puzzle Works
// the fundamental sliding mechanic
A single cell stays empty. Only tiles adjacent (up, down, left, right) to the empty cell can slide into it.
Click a numbered tile adjacent to the empty space to slide it in. No lifting, rotating, or jumping over tiles allowed.
Arrange all 15 tiles in order 1β15 reading left-to-right, top-to-bottom. Empty cell sits at the bottom-right corner.
Why Count Your Moves?
// every move has a cost
Every tile slide increments the counter by 1. The optimal solution for an average 4Γ4 puzzle takes around 52 moves. Expert players aim for under 80 moves.
The Row-by-Row Method
// foundational strategy for beginners
Place tiles 1β4 in the correct top row. Use rotations to slot them without disturbing each other.
Place tiles 5β8 in the second row using the same row-by-row technique.
Handle the left column (9 and 13) with a special L-shaped rotation move.
Solve the remaining 2Γ3 or 2Γ2 block using cyclic rotations until complete.
3Γ3 vs 4Γ4 vs 5Γ5 β How Hard Is It?
// complexity scales exponentially
// The 5Γ5 puzzle has ~10^25 states β even powerful computers struggle to solve it optimally.
Expert Advice
// cut moves, increase speed
Row by row
Corners last
Plan ahead