Mouse
- Click a tile next to the gap: slide
- (if supported) Buttons: shuffle / reset
- (if supported) Drag: slide tiles
Overview 
Sliding Puzzle
슬라이딩 퍼즐
Slide tiles into the empty space until the picture—or the numbers—are perfectly ordered.
One empty space, endless routes—planning beats frantic sliding.
PuzzleClassicSpatial
Goal & Core Rules
Rearrange the tiles by sliding them into the empty space until the target picture or numeric order is achieved.
- The board has one empty space; only tiles adjacent to it can move into the gap.
- Each move slides a tile horizontally or vertically into the empty space.
- Repeat until the picture is assembled (or numbers are in order).
- Fewer moves and faster time usually mean a better score.
Controls
Keyboard
- Arrow keys: move the gap (if supported)
- R: reset (if supported)
- U: undo (if supported)
Touch
- Swipe: slide tiles (if supported)
- Tap: move an adjacent tile
- (if supported) Buttons: shuffle / reset
Beginner Tips
- Solve row by row (or edge by edge) instead of random moves.
- Keep the empty space near where you’re working to reduce wasted motion.
- On 4×4+, learn a standard last-layer technique; the final two rows/columns are the real puzzle.
Advanced Tips
- Use cyclic moves (3-cycles) to place tiles without disturbing solved parts too much.
- Plan ahead to avoid parity traps in numbered variants (some configurations are unsolvable).
- Track your move count and aim for cleaner “macro” sequences instead of micro-adjusting.
Origins & History
Sliding puzzles are a class of combination puzzles where pieces are moved by sliding along constrained routes. The famous 15 puzzle (also known as the Gem Puzzle) was “invented” by Noyes Palmer Chapman in the 1870s and became a major craze in the United States in 1880.
Timeline
- 1874 Noyes Palmer Chapman is said to have shown an early precursor of the 15 puzzle.
- 1879 Manufacturing and distribution expanded, including the ‘Gem Puzzle’ name.
- 1880 The 15 puzzle became a widespread craze in the U.S.
Notable People
- Noyes Palmer Chapman Credited with inventing the 15 puzzle
- Sam Loyd Later falsely claimed invention; popularized an unsolvable challenge variant
FAQ
Why does the last part feel hardest?
Because you must position multiple tiles while preserving what’s already solved—planning beats quick moves.
Are all starting positions solvable?
No for numbered n-puzzles: only certain permutations are solvable (a classic parity fact).
Is there an optimal strategy?
There are known methods; perfect shortest solutions relate to search/heuristics and can be computationally hard.