From the publisher's website:

This strategic game helps players focus their attention as they try to push six of their opponent’s 14 marbles off the hexagon playing surface. But there’s a catch: it takes two marbles to move one of your opponent’s marbles and three to move two. While the game seems simple, it’s not simplistic. Abalone’s six directions of movement require players to stay focused as they balance both offensive and defensive strategy. Set up the field with white marbles on one side - black on the other. During a turn, a player can move groups of three, two, or just one of their marbles. The marbles can be moved along a straight line or scooted to the side. If a player has a group of marbles that is larger than the opponent's marbles and they are touching, the smaller group of marbles can be pushed over, one space. If an opponents marbles are near the edge, they can be pushed off into the gutter. Push six of your opponents marbles off of the playing field to win.