Completing the game under specific conditions or achieving high ranks in 'The Mercenaries' will unlock various rewards:
- Infinite Ammo Weapons: Earned by achieving high ranks (A or S) in 'The Mercenaries'. These include the Infinite Rocket Launcher, Infinite Gatling Gun, and Infinite Assault Rifle.
- Costumes: Alternate outfits for Jill can be unlocked by completing the game multiple times or achieving certain ranks.
- Epilogues: Different epilogues for various characters are unlocked by completing the game.
- Difficulty Modes: Hard Mode is available from the start, but completing the game can unlock even tougher challenges.
Replaying the game on different difficulties and aiming for better ranks in Mercenaries is key to unlocking all content.