Sliding Puzzle — Number Tile Game
The sliding puzzle (also known as the 15-puzzle or n-puzzle) challenges you to restore a scrambled grid of numbered tiles to their correct order by sliding them into the empty space. Choose from eight grid sizes — 3×3 up to 10×10 — across four difficulty levels. A built-in timer, move counter, undo, and hint system let you track your progress and get unstuck whenever you need it.
Grid Sizes
The classic starter grid with 8 tiles and one empty space. Fast to solve and perfect for learning the basics.
The most famous configuration — 15 tiles, one gap. Familiar yet challenging; the target for most competitive solvers.
24 tiles require planning several moves ahead. Intermediate difficulty that rewards pattern recognition.
35 tiles and a single gap. Requires deep spatial reasoning and a solid row-by-row solving strategy.
48 tiles push you into long multi-step sequences. Suitable for experienced solvers looking for a serious challenge.
63 tiles demand patience and a systematic approach. Even small mistakes cost many extra moves to correct.
80 tiles make each session a marathon of logic. Recommended only for expert-level players with time to spare.
The ultimate challenge — 99 tiles and one empty cell. Expert difficulty on the largest available grid.
How to Play
Pick Your Grid
Select a grid size using the tabs above the board. Larger grids shuffle more tiles, making solutions harder to find.
Slide Tiles
Tap or click any tile adjacent to the empty space to slide it in. On desktop you can also use arrow keys to move tiles into the gap.
Reach the Goal
Place all tiles in numerical order from top-left to bottom-right with the empty space in the bottom-right corner.
Beat Your Best
Your best move count and time are saved for each grid size. Use the Stats button to review your records across all grids.
Game Features
- ⏱ Timer & Move Counter. Both start automatically on your first tile move. Pause mid-game and the timer waits for you.
- ↩ Unlimited Undo. Step back through your entire move history one tile at a time. Helpful when you realise a sequence went wrong.
- 💡 Hint System. A directional arrow highlights the optimal next tile to slide. Uses A* search for 3×3 grids and a greedy heuristic for larger ones.
- 🎯 Curated Levels. Browse handcrafted levels with target move and time goals. Three-star ratings reward efficient solutions.
- 💾 Auto-Save. Your game state is saved after every move. Close the browser and come back — you'll resume exactly where you left off.
Strategy Tips
- → Solve top row first, then left column. Place tiles 1 and 2 (or 1–4 for larger grids), then work downward. Trying to fix everything at once leads to undoing progress.
- → Cycle tiles without disturbing solved sections. Learn the 3-tile cycle pattern — it lets you rotate three adjacent tiles without moving anything else.
- → Use the hint sparingly. A single hint shows you the best immediate move. Relying on multiple hints in a row negates the satisfaction of solving it yourself.
- → Use keyboard arrows. On desktop, arrow keys let you slide tiles faster than clicking. Up/Down/Left/Right moves the tile on the opposite side of the gap in that direction.
Frequently Asked Questions
Is every puzzle solvable?
Yes. The puzzle generator starts from a solved board and applies random legal moves — so every generated puzzle is guaranteed to have a solution.
What is the hardest grid?
The 10×10 (99-puzzle) is the most challenging. On Expert difficulty it applies up to 1,640 shuffle moves, producing positions that can require thousands of moves to fully resolve.
Is my progress saved?
Yes. Your current game is saved to your browser's local storage after every move. Your best times and move counts for each grid size are saved permanently until you clear your browser data.
Can I play on mobile?
Yes. The board is fully touch-optimised and resizes automatically to fit any screen width from 320 px upward.
How does the hint work?
For the 3×3 grid, hints use A* search with a Manhattan-distance heuristic to find the optimal next move. For 4×4 and larger, a greedy one-step lookahead picks the move that most reduces the total Manhattan distance.
How is the three-star rating calculated?
Curated levels have optional target move counts and time limits. Beating both targets earns 3 stars; meeting one earns 2; completing the level earns at least 1 star.