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.
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