小青蛙过河游戏。青蛙只能向前方空地移动一格或者跨过一只青蛙移动一格，红绿两方全部交换位置成功为获胜。-Small Frogger game. Frogs can only move one space to the open space in front of a frog or moving across a grid, both red and green all successful exchange position for the win.