No One Lives Forever 

Ingame just press 'T' and then enter the fillowing codes: 

Code Effect: 

mpimyourfather -- God mode on/off 
mpwegotdeathstar -- Infinite ammo 
mpkingoftehmonstars -- All weapons and full ammo 
mpmimimi -- All weapons and full ammo 
mpmaphole -- Complete mission 
mpdrdentz -- Fill health 
mpwonderbra -- Fill armour 
mpyoulooklikeyouneedamonkey -- Add all armour options 
mpgoattech -- Add all weapons upgrades 
mpmiked -- Exit game 
mpbuild -- Show game build 
mpasscam -- 3rd person view on your character 
mppos -- Show position on/off 
mprosebud -- Spawn snowtruck 
mpracerboy -- Spawn snowtruck 

- Unknown effect codes: 

mpexorbitantamounts 
mphookmeup 
mpcampos 
mpwhoami 
mpbeenthere 
mpcam 
mpbreach 
mptriggers 
mpboyisuck 
mppoly 
mpfov 
mplightadd 
mplightscale 
mpcamera 
mpwmpos 
mpwpos 
mpsanta 
mpteleport 
mpclip