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