Enable the console in the options menu then press ~ or TAB to open the console. 

Type "dipstick" to enable cheats.

Code             Effects

--------------------------------

God            - Godmode

Fly            - Flymode

Walk           - Walkmode

Chojin         - Godmode+infinity ammo+excalibat

Gunfinity      - Infinite Ammo

Shootme        - Bulletproof Armour

Burnme         - Asbestos Armour

Vanilla        - Bazooka

Hottimes       - Heat-seeker

Booze          - Drunk Missile

Splitem        - Split Missile

Bones          - Flamewall

Firebomb       - Firebomb (lamest cheatcode ever)

Kesofdeath     - Dark Staff

Homerun        - Excalibat

Cujo           - Dog Mode

Seeya          - God Mode

Flyboy         - Mercury Mode

Boing          - Elasto Mode

Badtrip        - Shrooms Mode

setsensitivity - Set mouse sensitivity

setres         - Set your screen resolution

exit           - Exit the game prostyle

disconnect     - Don’t try this at home

reconnect      - This either

gamma          - Adjust your gamma!

showhud        - Remove the HUD (great for screenshots)

capturemode    - We think this does the same thing as showhud

say            - It’s like talking

fly            - For when you’ve had enough of walking

walk           - For when you’ve had enough of flying

slomo          - Enter the Matrix. Slomo from .1 to .9 to slow your roll, bro.

start          - Start a level

setgroundspeed - Gotta go fast!