It's a numbers puzzle game. The aim of the game is to get each number on a 3x3 board of numbers to be exactly the same. One of the numbers is always selected. This number can be moved by using swipe. Each time you move the selector, the number you select will increase in number by one.
Starting from the level 51 it becomes a little more complicated. The board contains dark and bright tiles, each of which has different behaviour. Stepping on bright tiles increases the numbers by one, whereas stepping on dark tiles decreases the numbers by one.