15 is a classic puzzle game available for Android devices. The game is also known as Game of Fifteen, which was invented in 1878 by Noah Chapman. The game consists of a set of identical square tiles with numbers applied to them, enclosed in a square box. The length of the box is four times the length of the side knuckles for a set of 15 elements, and in the box, one square field is left blank.

The objective of the game is to move the knuckles of the box to achieve the ordering of numbers, making as few moves as possible. The game is a great way to improve your problem-solving skills and is suitable for players of all ages. With its simple and easy-to-use interface, 15 is an excellent choice for puzzle game enthusiasts.