Super Hard difficulty:
To unlock Super Hard difficulty, beat the game on the default difficulty setting.
Unlock the following challenge rooms by entering the corresponding sequences of buttons at the "Press Start" screen:
CHALLENGE ROOM - CODE
Aaron Sedillo challenge room - right, down, left, up, L1, R1, triangle, triangle, X, X, start.
EuroGamer challenge room - down, up, down, up, left, L1, square, L1, square, triangle, start.
GamesRadar challenge room - R1, triangle, square, square, up, down, L1, L1, Up, Down, start.
IGN.com challenge room - up, down, triangle, square, square, triangle, down, up, L1, L1, start.
Major Nelson challenge room - L1, square(3), right, down, L1, left, triangle, down, start.
Cat burglar - Get to the boss of Area 05 within one minute and thirty seconds.
Clean as a whistle - Clear Area 02 without touching a slime blob.
Faster Than a Speeding Bullet - Block 100 projectiles using the claw.
H4><0rz - Hack through all the hacking games on Hard.
Meet with annihilation - Kill all foot soldiers and enemy trucks on a Meet With Enemy sequence.
Pacifist Pride - Clear any of Area 01 - 12 without firing your gun.
The Emperor's New Clothes - Obtain the Shin Guards, the Bulletproof Vest and the Helmet.
Elite Commando - Clear the game on Super Hard.
Intel Collector - Acquire all database logs.
One Dozen Yashichis - Collect all 12 hidden Yashichis - one from each of Area 01 - 12.
Private Arsenal - Obtain every weapon and weapon upgrade.
A Real Challenge - Acquire at least one star in each of the Challenge Rooms 1 - 56.