According to Deb of ICVZ, "Marco Cerigioni, in his book "Avoid Missing Ball", says French company Jeutel exposed Zero at a London Exhibition (ATEI?) for a few hours, then Scotland Yard confiscated the game. Then, at Milan Fair, there were three version of Defender: the original one, Jeutel's Zero and the Amtec/Videogames GmbH bootleg called Tornado. This is the only mention of "Amtec's Tornado" I found. I've never seen a unit with this name. However, I've never seen a "Zero" unit, also. They were rare and many local distributors got rid of these bootlegs in a hurry, since the war against pirates had started."
ICVZ currently states "It was distribuited with two names; Zero, like the PCB used for dumping, and Tornado, as written in a flyer.."