小球游戏,小球在屏幕上自由移动,碰到挡板或墙壁即发生弹性碰撞,如果挡板未接住小球,或碰到下墙壁则游戏结束.-Ball game ball to move freely on the screen, hit the wall that is lagging or elastic collision occurs, if shutter not catch the ball, or run into the next wall is the end game.