To do any cheat you must first enter the hacking section and type: CHEAT.EXE

Alternatively follow the commands until cheats beome available in the hackers menu.

Once either of these are done you can enter any of the following cheat codes:

Infinite Health:
7F4DF451

Infinite Focus:
69E2D9E4

Fast Focus Restore:
FFF0020A

Infinite Ammo:
1DDF2556

All Weapons:
0034AFFF

Faster Logos:
7867F443

Turbo Mode:
FF00001A

Extra Bonus Level (Sparks' training level):
13D2C77F

God Mode/Invisibility (enemies cant see you):
FFFFFFF1

Enemies Cant Hear You:
4516DF45

Multiplayer Fight:
D5C55D1E

Low Gravity:
BB013FFF

Taxi Driving:
312MF451