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.
- Arcade fun made portable - The full glory of the METAL SLUG arcade experience has been perfectly captured on the PlayStation Portable with signature off-the-wall military "run and gun" gameplay, colorful, cartoony humor and the opportunity to play together with a friend.
- Multiplayer METAL SLUG - Get the full METAL SLUG experience that recalls the good old days of gaming with your friends when you join up over local wireless to take on missions in 2-player co-op ad hoc mode.
- Play again and again - Uncover something new on every playthrough! Choose between 3 difficulty modes and six playable characters that offer unique weapons and attack moves. Seven levels with diverging paths challenge you with different enemies and obstacles. Combat School tests the true METAL SLUG fan with more than 70 mission-based trials that determine military rank.