CETI 21

The moon base, CETI 21's security system was being upgraded. That was until a fatal computer crash on the mainframe has occurred. Now the force-field barrier has been shut down, and now the aliens have ransacked the computer. Defenses have turned against us. Luckily Ultrax 18 drones can be piloted by you. Your mission is to guide Ultrax 18 through all 3 zones in CETI 21. Fight your rogue defenses, and alien ships. Avoid shooting your own ships/drones. If you destroy any of these, you will have to pay the price of one of your precious lives. Can you reach the mainframe, and destroy it - and end the aliens ransacking CETI 21?