Remove all the numbers. Two numbers can be removed by clicking on them. Those numbers must be next to each other vertically, or next to each other horizontally. That includes the case where one is at the end of a row and the other is at the start of the next row. The numbers must be the same or their sum must be 10. When there are no more numbers that can be removed, the remaining numbers are appended again to the end, hopefully creating new possibilities to finish the game.
The game is also known as TenPair, Numberama, Take Ten, 10 Seeds, Digits.