Metal Slug | Advance

You must finish a mission without dying after collecting a card to keep it. The "Paper Thin" Card

In Mission 3, you can find it by shooting the corner of a specific block in the first secret cave area. Metal Slug Advance

While some are just for display, many cards grant gameplay bonuses like increased weapon power, new "Slug" modifications (like the Slug Gunner ), and access to hidden map routes. You must finish a mission without dying after