To unlock Tofu mode, beat Operation Javier - Chapter 5 on Normal. It will become available in the "Secret" option located in the bottom right corner of the main menu.
Unlockable Difficulties:
To unlock Very Easy difficulty, beat the game 10 times on Easy.
To unlock Very Hard difficulty, beat the game on Hard.
Krauser Bonus scenarios:
To unlock the Krauser Bonus scenarios, beat Operation Javier - Chapter 7 in less than 10 minutes.
Operation Javier: Chapters 6 & 7:
To unlock Operation Javier: Chapters 6 & 7, defeat the Boss in Chapter 5 as quickly as possible to save your partner.
S.T.A.R.S. mission:
To unlock the S.T.A.R.S. mission, beat the Secret Chapters.
Linear Launcher:
To unlock the Linear Launcher, beat all chapters on Hard difficulty.
Alternate costumes:
Unlock the following alternate costumes by performing the corresponding tasks:
Chris' Caucasus costume - Beat Operation Javier - Chapter 5 on Normal.
Chris' Mafia costume - Get an "S" rank on Game Of Oblivion - Chapter 7 on Normal.
Claire's Biker costume - Get an "S" rank on Memories Of A Lost City - Chapters 1 through 8 on Normal.
Claire's Western costume - Get an "S" rank on Game Of Oblivion - Chapters 1 through 7 on Normal.
Krauser's Detective costume - Get an "S" rank on Operation Javier - Chapters 1 through 5 on Normal.
Krauser's Mercenary costume - Beat Operation Javier - Chapter 5 on Normal.
Leon's Agent costume - Beat Operation Javier Chapter 7 on Hard.
Leon's Biker costume - Get an "S" rank on Memories Of A Lost City - Chapters 1 through 8 on Normal.
Leon's Detective costume - Get an "S" rank on Operation Javier - Chapters 1 through 5 on Normal.
Leon's R.P.D. costume - Beat Operation Javier - Chapter 7 on Hard.
Steve's Western costume - Get an "S" rank on Game Of Oblivion - Chapters 1 through 7 on Normal.
Achievement titles:
Unlock the following Achievement titles by performing the corresponding tasks:
Bomber - Use 50 grenades.
Executioner - Get 200 head shots.
Game Cleared (Easy) - Beat all chapters on Easy.
Game Cleared (Hard) - Beat all chapters on Hard.
Game Cleared (Normal) - Beat all chapters on Normal.
Head Hunter - Get 100 head shots.
Head Shooter - Get 50 head shots.
Hunter Killer - Kill 100 Hunters.
Licker Killer - Kill 50 Lickers.
Put Trust In Others - Have your partner kill 30 enemies.
S.T.A.R.S. Mission - Beat the secret mission.
Trigger Happy - Fire more than 10,000 rounds.
Ultra-Rich - Collect 150,000 coins.
Wealthy - Collect 100,000 coins.
Well-Off - Collect 50,000 coins.
Zombie Hunter - Kill 500 zombies.
Zombie Killer - Kill 1,000 zombies.
Zombie Shooter - Kill 100 zombies.
More Achievement Titles:
To unlock additional Achievement Titles, beat each chapter on Hard without dying.
Alternate endings:
To unlock the Bad ending, beat Operation Javier: Chapter 5 in over 10 minutes. To unlock the Good ending, beat Operation Javier: Chapter 5 in under 10 minutes.
