Click or tap on one of the buttons reduces that button’s number by 1 as well as those of the four surrounding buttons. Your aim is to set all the buttons to ‘0’ in as few taps as possible. You can go back a move and restart a puzzle.
The Puzzle levels go from 1, which is very simple, up to 9 which is fiendishly tricky! There is no regular method of solving but, if you doubt that a puzzle can be solved, you can hit the emergency