The sliding puzzle (also called a 15-puzzle) is a classic brain teaser. You have a 4×4 grid with 15 numbered tiles and one empty space. The tiles are scrambled, and your goal is to arrange them in order from 1 to 15 by sliding tiles into the empty space.
Click or tap a tile adjacent to the empty space to slide it over. You can only move tiles that are directly next to the gap — up, down, left, or right. Plan your moves carefully, as moving one tile always affects the position of the empty space.
A good strategy is to solve the puzzle row by row, starting from the top. First, get tiles 1–4 into the correct positions in the top row. Then solve the second row (5–8) without disturbing the first. For the last two rows, work on the left columns first.
Try to solve it in as few moves as possible. This free online version tracks your move count and works on both desktop and mobile devices.