After General Morden is defeated and captured, a mysterious army arrives from the future to save him. They reveal themselves to be the Mars People and their goal is to provide their future leader with special advanced weaponry to take on his enemies in the present. Classic Metal Slug characters Marco, Tarma, Fio, Eri, Ralf, and Clark return once again to take on General Morden and his new and improved Rebel Army. Metal Slug XX is a side-scrolling, arcade-style, run-and-gun shooter for PSP where players can choose between six zany characters and shoot through seven action-packed levels with varying obstacles, numerous enemies, and diverging paths. Confident players can put their skills to the test by playing more than 70 mission-based trials in "Combat School." With its unmistakable style and personality, nostalgic gameplay, more than 70 missions, and the ability to play with a friend, Metal Slug XX is the definitive portable Metal Slug arcade experience.