The game has the field size 3x3, that has eight balls. A gamer may move those balls to empty place. The goal is find the same sums of row and column. From mission to mission game is becoming harder, rules are becoming more complex. The gamer has to remember a math and stay calm. Just try it!
https://play.google.com/store/apps/details?id=my.game.crossball
https://play.google.com/store/apps/details?id=my.game.crossball