War for Diamonds
With a right-click all adjacent same-coloured stones can be deactivated from the board. Since you want to deactivate as many stones as possible, you may want to move some of them around the board by clicking on them. The stone will have to sit beside the free place.
You only have a limited time period of 30 seconds to deactivate the next bunch of stones. In case you deactivated four or more stones your get your time period refreshed to 30 seconds. The more stones involved in a deactivation the more points.