Sliding Puzzle
Slide the tiles and put every number back in order!
🖱️ Click a tile next to the empty space · ⌨️ Arrow keys slide tiles
Sliding Puzzle Rules
The sliding puzzle (also known as the 15 puzzle) is a timeless brain teaser. An N×N board holds numbered tiles and one empty space. Slide a tile next to the space into it, and repeat, until all numbers run in order from left to right, top to bottom. Choose 3×3, 4×4 or 5×5 — every board is shuffled by sliding tiles from the solved state, so every puzzle is solvable.
Solving Tips
- Solve row by row: finish the top row first, then leave it untouched while you work on the next one.
- Rotate the last pair in: the final tiles of a row usually need to rotate into place together with the row below.
- Plan the empty space: think about where the gap needs to travel — fewer moves mean a better score.
The Puzzle That Drove America Crazy in 1880
The sliding tile puzzle is the grandfather of puzzle crazes. Attributed to Noyes Chapman, a postmaster from Canastota, New York, it swept the United States around 1880 so thoroughly that newspapers wrote about office workers abandoning their desks, and one famous challenge — swapping just the 14 and 15 while leaving everything else in place — offered a $1,000 reward nobody could ever collect, because that configuration is mathematically impossible.
Impossible, that is, unless you already know the parity rule that our shuffle respects: every deal we generate is guaranteed solvable. Solving in rows from the top down is the classic beginner method, and if you get hooked, mathematicians have proven no 4×4 deal needs more than 80 single-tile moves — a result that took a century of computer search to establish.
FAQ
How do you play the sliding puzzle?
Slide tiles into the empty space until all numbers run in order from left to right, top to bottom, with the space at the end.
Who invented the 15 puzzle?
The 15 puzzle was invented by Noyes Chapman in 1874 and popularized worldwide by puzzle master Sam Loyd.
Is every shuffle solvable?
Yes. Boards are shuffled by sliding tiles from the solved state, so every puzzle you get is 100% solvable.
What skills does it train?
Spatial reasoning, planning and concentration — a great everyday brain workout for all ages.
What is the best order to solve the sliding puzzle in?
Work from the top down: fix the first row completely, then the second, then solve what's left as a small 2×3 block. Once a row is locked, never move those tiles again — most beginner struggles come from disturbing finished rows to grab one tile that happened to be passing by.
Is a solution always possible from any shuffle?
On our site, yes — every shuffle is generated from the solved state by legal moves, so a solution always exists. Half of all imaginable arrangements are unsolvable, which is exactly what made the original 1880 reward challenges a safe bet for the newspapers offering them.