Which of these is NOT a game under the Worms series?

Major Malfunction is not a game under the Worms series because it is not an official title recognized as part of the Worms franchise. The Worms series is a popular turn-based strategy game in which players control a team of worms to battle against other teams. Major Malfunction, on the other hand, is a game developed by Artificial Mind and Movement (A2M) and published by Playlogic Entertainment. It features a different gameplay style and does not involve worms or the same mechanics as the Worms series. Therefore, Major Malfunction is not considered a game under the Worms series.