Slide puzzle
Tap a tile beside the gap. Tab to a movable tile and press Enter or Space, or use arrows to move the gap.
How sliding puzzles work
A sliding puzzle begins with numbered tiles and one empty space. Move a neighbouring tile into the gap, then keep making room until the numbers read in order.
Start with 3 × 3, also called the 8-puzzle. The 4 × 4 board is the 15-puzzle. Every board here is made with legal slides, so there is always a way to finish.
Rules, hints and a first strategy