🧩 Fifteen
The classic sliding-tile puzzle. Order the numbers with the gap last.
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How to play Fifteen
- Pick a grid size, then press Start to shuffle a fresh board.
- Slide a tile into the empty gap by tapping it or using the arrow keys.
- Tap any tile in line with the gap to slide the whole row or column at once.
- Arrange the numbers in order, left to right and top to bottom, with the gap in the last square.
Controls
| Input | Action |
|---|---|
| Arrow keys / WASD | Slide a tile toward the gap |
| Tap a tile | Slide it (or its row/column) |
| Swipe | Slide on touch |
| Ctrl+F | Enter or leave full screen |
| Esc | Leave full screen |
Tips & strategy
- Solve the top row and left column first, then you never have to disturb them again.
- On 4×4 and 5×5, finish each row's last two tiles together using the corner rotation trick.
- Every shuffle is reachable from solved, so there is always a way back — no board is a dead end.
- Your best is the fewest moves to solve, tracked separately for each size.
Frequently asked questions
Is the 15 puzzle always solvable?
Here, yes. Boards are scrambled by making random legal slides from the solved state, so a solution always exists — unlike a blind tile shuffle, which is solvable only half the time.
What do the colours mean?
A tile glows in the accent colour once it is sitting in its correct final position, so you can see your progress at a glance.
How is my score tracked?
Your record is the fewest moves to solve, saved per grid size in your browser.