The object is to slide numbers up/down/right/left and combine them with each other and then match the number in the white square.
Look at the third image. See the instructions in English? When I downloaded the game, my instructions came in Russian. No matter, the pictorial rules are straight forward.
You must slide the tiles and combine them to enter the white square. You can slide in all directions. However, the value of the tile which you are sliding will decrease in value. Look at the fourth image. See the 4? If you slide it down, it will become a 2, because it went down 2 squares.
I did the first 25 levels. They get hard!