How to play
Tap any tile in the same row or column as the empty space to slide it — and every tile between — toward the gap. You can also swipe on the board or use the arrow keys / WASD, which move the tile next to the gap in that direction. Put the numbers in order from left to right, top to bottom, to win.
Is every puzzle solvable?
Exactly half of all random arrangements can never be solved. This puzzle checks the shuffle with the classic parity rule and fixes it before you start, so every board here has a solution.
Tips
Solve the top row first, then the left column, so the puzzle shrinks to a smaller one. Place the last two tiles of a row together: park them in a column below their spots, then rotate them in. Your fewest moves and fastest time for each size are saved in this browser.