In the third installment of the Metal Slug series, General Morden is back and he plans to establish a new world order. The player guides one of the heroes: Marco, Tarma, Eri, or Fio, as they blast their way through side-scrolling levels with a unique theme, filled with countless enemies and bosses. The player has to free hostages and can ride bizarre vehicles such as camels, elephants, tanks, and robots.