Start Mission 1
Complete Mission 1 with no continue
Reach the icy cave's exit with the Elephant Slug
Clear Mission 2 as a zombie
Play all the routes
Find and save Hyakutaro Ichimonji
Complete Mission 2 with no continue
Complete Mission 3 with no continue
Complete Mission 4 with no continue
Complete Final Mission with no continue
Complete all the missions
Achieve over 3,000,000 points
Ride all the Slugs
Defeat any boss in the game with the METAL SLUG ATTACK