Extra Costumes
Complete the game using the normal or hard difficulty setting to get the Closet Key. Use this in the room where you found the Hunting Gun for extra costumes.
100% success rate. 

Leech Hunter Mini-Game
Complete the game with a B, C or D rank for the Leech Hunter mini-game.

Leech Hunter Game Rewards

• 100 Leeches: Unlimited ammunition for any weapon.
• 90-99: Magnum Revolver in room 202 of the Train.
• 60-89: Unlimited ammo for the Hunting Gun.
• 30-59: Equipped handguns have unlimited ammo.
• 1-29: Submachine Gun bullets added to Rebecca's inventory.

A Rank Rewards
Complete the game between 3:31 and 5 hours for an A rank to unlock the Submachine Gun and the Leech Hunter mini-game.

S Rank Rewards
Complete the game in 3:30 or faster for an S rank to unlock the Rocket Launcher, the Submachine Gun and the Leech Hunter mini-game.

Go to: Resident Evil Zero Info Page | nGaming Home Page.