Threes puzzle app screenshotThrees is a tiny puzzle that grows on you.

The goal is to combine tiles on a 4×4 grid by sliding them into other tiles with the same numbers on them. Two threes combine to form a six, two sixes form a 12, and so on. You don’t slide individual tiles or rows, though — you slide every tile on the board in the same direction whenever you swipe. A new tile appears every time you swipe. Once the board is full and there are no possible combinations left, the game ends and your score is calculated.

Free for iOS and Android.