Threes! for iPhone

Threes is a challenging, addictive puzzle game that tasks you with moving numbered tiles around on a board to create multiples of three. Each time you make a move, a new tile is added, and you can keep going until there are no tiles left to combine.

Pros

Challenges and Game Center: Beating your own high score might be enough motivation at first, but when you want want an extra push, check out the Challenges. At any point during a game, you can switch to the Challenges screen to see how all your game stats -- and not just your total score -- measure up against your personal bests. You can also challenge your friends and track your progress against players worldwide through Game Center.

Fun design: Threes has some nice design touches that you might not expect but that make it more fun to play. For instance, look closely at the tiles and you'll see that they have tiny faces across their bottom margin, and these faces change as you move and combine them. The sound effects that go with each movement and combination are also quite cute.

Cons

Sound bugs: The game's sound didn't always work during testing. Even after repeated adjustments in the Settings menu, it would come on during some sessions and not during others.

Bottom Line

Threes is an easy way to kill a few minutes or a few hours. Though the mechanics of the game are fairly easy, the challenge of creating tiles with higher and higher values will keep you coming back.