"15" is a classic sliding puzzle game that dates back to the 19th century. The game consists of a square grid with numbered tiles that can be slid horizontally or vertically. The grid typically has dimensions of 4x4, containing numbered tiles from 1 to 15 and an empty space.

The objective of the game is to rearrange the numbered tiles in ascending order by sliding them into the empty space. The challenge lies in the limited movement allowed—only adjacent tiles to the empty space can be moved. Players need to strategize and plan their moves carefully to solve the puzzle.

The game starts with a randomized configuration of tiles, creating an initial disorder. The player must analyze the current arrangement and make a series of moves to achieve the goal of having the tiles ordered from 1 to 15. The empty space serves as a maneuvering tool, allowing players to shift tiles around the grid.

"15" is renowned for its simplicity yet requires a good deal of logical thinking and problem-solving skills to complete. The number of possible combinations increases the complexity of the puzzle, making each playthrough a unique challenge.

This classic game has been adapted into various digital formats, retaining its fundamental mechanics while offering players the convenience of virtual play. It continues to captivate players of all ages, providing an enduring and engaging puzzle-solving experience.