+ & - : A Zen game

The object of this game is to get a high score. Your working on a 16 square grid that contains two colors. Sounds simple right. You achieve this goal by adding and subtracting numbers. However, there are rules that govern how this math can be done. To add, both numbers must be the same and come from the same color. To subtract, the numbers must be different and come from different colors. You'll find that you' ll often make a mistake and when you do, another number will be added to the grid. Once the grid fills up, it's game over. Going for the highest score possible isn't easy. Part of the problem is that there is no Save Game Feature. So you must achieve your best score all in one sitting. If they add this feature, this will be one of the best apps you can get, hands down.