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.

In the Xbox version, additional game modes, such as Storming the Mothership and Chubby Isle Paradiso, can be unlocked upon completing the five arcade stages. A co-op mode has been included, but no online multiplayer. The only Xbox Live feature available allows the player to compare single-player scores.