Metal Gear Solid: Portable Ops/Unlockables

There are many features that can be unlocked in the game.

Stealth Camo
In order to unlock the Stealth Camo, you need to attain a Tech level of 99.

Extreme Difficulty
In order to unlock the Extreme Difficulty, you need to beat the game once.

Boss Rush (EU only)
In order to unlock the Boss Rush mode, you need to beat the game once.