The codes have to be entered in pause mode [Esc]:

 To be activated in any mode:

 painless      Gode mode
 fogging       Toggle fog
 followme      Different camera view

 To be activated in Sharpshooting mode:

 weapons       All weapons
 ammo          Unlimited ammo
 autoreload    Toggle auto reload
 autofire      Toggle auto fire
 slowmo        Enemies move slower
 slowrocket    Rockets are slower

 To be activated in Driving mode:

 ghost         Drive through walls
 nitro         Unlimited nitro
 freeze        Toggle time limit
 chantastic    More speed
 snow          Snow
 susonly       Only tires visible

 To be activated in Action/Adventure mode:

 weapons       All weapons
 ammo          Unlimited ammo
 freeze        Freeze enemies
 targeting     Toggle auto targeting
 laser         Toggle laser targeting
 ghost         Walk through walls
 followterrain Jump extremely high
 mrbones       Become a skeleton
 shocked       Become electric
 fps           First person view
 fragyuck      Gore mode
 pillowmode    Small heads
 bighead       Big heads