# Completion bonuses

Successfully complete Story mode with Marco to unlock the Monolith with infinite ammunition and the Extras menu (with "Mini Game", "Color Edit", "BGM Test", and "Movies" options).
# Laboratory staff

Collect the CDs hidden in the various locations in all missions. Then, enter the "Garage" screen and select "Laboratory". The staff will be found inside.
# Slug Gunner

Add the Gunner Core, Gunner Arm, Gunner Cannon, and Gunner Leg to Metal Slug in the Slug Laboratory.