Goal: slide the numbered tiles through the empty space until
they read in order, left to right, top to bottom.
The rules
- Click (or tap) a tile next to the empty gap and it slides over.
- Tiles already in their final spot glow green — use them as signposts.
- Pick a board size: 3×3 warm-up, 4×4 the classic 15 puzzle, 5×5 for the brave.
Controls
- ←→↑↓ slide a tile into the gap from that direction.
- U undo · N new shuffle · R rules.
Good news
- Every shuffle starts from the solved board and slides backwards, so it is always solvable — no impossible deals here.
- Moves, time and your best solve per size are saved in this browser.