15 Puzzle
Slide the numbers to solve
Frequently Asked Questions
Have another question? Let us know.
How do I move the tiles?
Click on a numbered tile adjacent to the empty space to move it. You can also use keyboard arrow keys: pressing Up moves the tile below the empty space upward, and so on.
What difficulty levels are available?
We offer four grid sizes: 3×3 (8-puzzle), 4×4 (classic 15-puzzle), 5×5 (24-puzzle), and 6×6 (35-puzzle). Beginners should start with 3×3, while experienced players can challenge larger grids.
Are all puzzles solvable?
Yes, we use a special shuffling algorithm to ensure every generated puzzle is solvable. According to mathematical principles, approximately half of all random arrangements are unsolvable, but we filter these out.
How can I view my best scores?
The game interface displays your best move count record for the current grid size. Data is saved in your browser's local storage.
Can I undo moves?
Yes, click the undo button or press the Z key to revert your last move.
What is the win condition?
Arrange all numbered tiles in order from left to right, top to bottom, with the empty space in the bottom-right corner.
Any tips for solving?
A common strategy is to complete the first row, then the first column, then work on the remaining sub-grid. For 4×4 and larger, learn the 'layer method'—solve layer by layer rather than moving tiles randomly.
Explore Game Details
About the Game
The 15 Puzzle (also known as the Sliding Puzzle or Gem Puzzle) is a classic brain teaser. The game consists of numbered tiles from 1 to 15 and one empty space. Players must slide the tiles to arrange all numbers in order. Originating in 19th-century America, it quickly became a global sensation and remains a timeless test of logical thinking and spatial reasoning.
The 15 Puzzle, alongside China's Huarongdao (Klotski) and the Rubik's Cube, is considered one of the world's three great puzzles. It appears simple but contains profound mathematical principles—not all random arrangements are solvable, which relates to the parity of inversion numbers. Our game guarantees every generated puzzle is solvable and offers four difficulty levels: 3×3, 4×4, 5×5, and 6×6 grids.
Psychology Behind the Game
Cognitive Skill Enhancement
The 15 Puzzle requires players to simultaneously use visuospatial reasoning and working memory. You need to construct a mental model of the current layout, predict the consequences of each move, and plan multi-step solutions. Research shows that regularly playing such games can improve working memory capacity and spatial cognition.
Problem-Solving Strategies
Solving the 15 Puzzle typically employs a divide-and-conquer strategy—complete the first row or column first, then proceed with the remaining sections. This local-to-global approach is a common algorithmic thinking pattern in computer science and mathematics, greatly benefiting the development of logical reasoning skills.
