When in single player mode, please use the mouse to move In double mode, 1P uses W and S to control up and down; 2P uses up and down keys. Just hit the ball back. (單人模式時，請用滑鼠移動若是雙人模式，1P用W，S控上、下；2P則用上鍵、下鍵。只要把球打回去就可以了。)
There can be errors. (有錯誤可提出)
