The trend in the App Store currently leans towards simple games, which have addiction potential: Flappy Birds started it all and games like “9” or “10”, as well as Threes!, follow the same line. The objective in Threes! is to cleverly combine numbers on a board, which features 16 blocks (4×4), ending up with a fairly high total score.
It might sound simple, but does require concentration. When you perform swiping motions, the blocks of numbers move along. Also, not all numbers can be combined with each other. New cards are constantly being added to the board, and you have to make sure it does not fill up. You will find this combination of math, puzzle and hectic quite challenging.