you try to protect the escaping Rebel transporters as many as possible. You have to use the Ion cannon which have the power to destroy a giant space ship. Move your mouse to target the Ion cannon and press the mouse button to fire at will, and the Ion cannon can be moved to get a better fire position. But be careful, do not fire at the escaping Rebel transporters, or a life will be taken! When you fire too heavy, the Ion cannon will run hot. When maximum heat is reached the Ion cannon will below and a life will be taken, either!