The game starts as soon as the player touches the tiles. The challenge is to select a group of adjacent numbers that sum to the target number. For example to reach 5 you might select 1,2,2. Valid tiles are horizontally or vertically adjacent to the last selected tile. The first tile for each selection can be chosen freely. Once the player removes his or her finger, or releases the mouse, the selection will be cleared and, if correct, the target number will increase by one. There is no penalty for releasing a selection and starting a new one. Reaching the target number by more complex combinations of numbers will result in a 5 second time bonus. Players are challenged to get as high in target numbers as possible.
The resource is designed to provide practice for common, small value, additions. It could be usefully used for practice in class or, due to its wide compatibility, for homework.