Gameplay consists of sliding numbered blocks onto one another to form higher numbers, but some important rules turn an easy concept into a challenging puzzle. Only like numbers can combine together, for instance, 3 and 3, to form a 6, which can then only combine with another 6. 1 and 2 are limited to combining with each other.
Each slide produces additional numbers on the board, and the idea is to continually clear numbers by combining them, because the game ends when the board is full. Our sister site TouchArcade has published a review of Threes!, essentially calling it simple, accessible, and well-designed.
Games of Threes! quickly escalate to an epic dance of block management, as much like the classic puzzlers we grew up on, you're given a hint of what's coming next in the form of a red "2" block, a blue "1" block, or a white numbered block. When you slide the blocks in a direction, whatever block is next slides in from the opposite direction, leaving you with a shocking amount of things to consider each time you place your thumb on the screen.TouchArcade gives Threes! five stars and says that it is "about as close as it gets to a perfect mobile game." The site has also posted a TA Plays video depicting the gameplay.
For each flawless movement, without some intense analysis, there's also an equal chance that you’ll accidentally make an unintended combination and in turn wind up with a block you can't immediately using junking up one side of the game board.
Threes! is a universal app that can be downloaded from the App Store for $1.99. [Direct Link]