Number-philes out there sick of Sudoku have another game they can sink their teeth into with Quadion's Nine Gaps. The game is relatively simple, place nine numbers in nine empty gaps on the board that's setup in a three by three grid. I'm guessing you get why they named the game nine gaps?
Nine gaps isn't as simple as randomly placing down numbers on the board. Each gap is separated by a mathematical symbol: add, subtract, multiply and divide. No need to worry about those pesky exponents and such, only simple math. As you plop the numbers down by dragging them from the top of the screen into their spaces they must equal the amounts stated on the right and bottom of the board. Oh, and you can only use each number once.
The game provides three levels of difficulty and depending on the difficulty you choose Nine Gaps either fills in some spaces to make it easier or leaves you fending for yourself on an all-empty board. Puzzles can be frustrating at times but will have you coming back for more. Nine Gaps keeps a record of your best times and you'll find yourself consistently trying to one-up yourself.
There's also no need to worry about the running out of puzzles as all of them are randomly generated. You could play for years and would most likely never run into the same puzzle.
The concept behind Nine Gaps isn't a new one. Some of you might remember playing similar pen and paper games in school to help you learn math. The game plays on this fact as the board is a piece of lined paper and the numbers are you drag place in it are ripped squares of paper, much like a kid had made the game at home. Seriously, the game looks like someone grabbed some paper and made it in 10 minutes to teach his or her little brother some math. Enhancing the little kids feel, every time you finish a puzzle is a chorus of kids cheering. As a note, playing the game with your iPhone or Touch at full volume on the bus will definitely get you strange looks from your fellow commuters. Trust me.
Nine Gaps is a simple game with a simple design and does it simply perfect. For a buck this games worth a whirl.