Slide the numbered tiles to arrange them in order. Tap or use arrow keys.
Choose a grid size:
The sliding puzzle (also known as the 15-puzzle) is a classic combination puzzle where you slide numbered tiles on a grid to arrange them in numerical order. Invented in 1874, it became one of the biggest puzzle crazes of the 1880s and remains a beloved brain teaser today. This free online version lets you play three grid sizes — from the beginner-friendly 3×3 up to the challenging 5×5 — right in your browser.
Choose your grid size, then tap or click any tile adjacent to the empty space to slide it. You can also use arrow keys to move tiles. The timer and move counter start on your first move. Correctly placed tiles get a subtle green highlight to help you track progress. Beat the puzzle and try to set a personal best — your records are saved for each grid size.
Solve row by row from top to bottom. Place the first row in order, then the second, and so on. For the last two rows, work column by column. The key is to move tiles into position without disturbing those already placed — use the empty space to create temporary paths around fixed tiles.
No — exactly half of all possible configurations are solvable. A position is solvable only if its inversion count has the correct parity relative to the empty space's row. This game always generates solvable puzzles by scrambling from the solved state using valid moves, so every game can be completed.
The hardest 15-puzzle configurations require a minimum of 80 moves to solve optimally. On average, a random solvable configuration needs about 50 optimal moves, though human solvers typically use many more. Finding the shortest solution is NP-hard.
If you enjoyed this, try these: Sudoku · Jigsaw Puzzle · Nonogram
Last updated: March 2026 · whatifs.fun — Free interactive games, experiments & simulations