Load the game with the "+developer 1" comand line parameter (i.e., "c:\Kingpin\kingpin.exe +developer 1"). Then, during the game, press ~ (tilda) key to display the console prompt and enter one of the following codes to activate the corresponding cheat function:

god - god mode
immortal - god mode
noclip - no clipping mode
cl_rearviewmirror 1 - see behind you
togglecam - enables third-person view
notarget - your opponents will ignore you
extracrispy - sets enemies on fire
key# - the number of key you want from 1-10

give x - where x is the item you want (see below)

all
weapons
ammo
cash ###
coil
watch
battery
whiskey
chem_plant_key
fuse
shop_key
warehouse_key
lizzy head
shipyard_key
office_key
valve
ticket
flashlight
crowbar
pistol
shotgun
tommygun
heavy machinegun
grenade launcher
bazooka
flamerthrower
bullets ###
shells ###
308cal ###
grenades ###
rockets ###
gas ###
spistol
pistol reload
small health
large health
adrenaline
health
helmet armor
jacket armor
legs armor
armor

map [map name] - play slected map (see below)

Map Names:
sr1 - skid row
sewer - the sewers
sr2 - the super
bar_sr - jax
sr3 - mean streets
sr4- the Jesus
bike - bike
pv_h - poisonville
bar_pv - club swank
pv_1 - Louie's errand
pv_b - Blanco industries
pv_boss - Nikki Blanco
sy_h - Lizzie's problem
bar_sy - salty dog
sy1 - pier pressure
sy2 - das boot
steel1 - steeltown
bar_st - boiler room
steel2 - steel mill
steel3 - steel processing
steel4 - moker shipping
kpcut3 - consequences
ty1 - derailed
ty2 - dark passage
ty3 - trainyards
ty4 - depot
kpcut4 - the picnic
rc1 - radio city station
rc2 - enter the dragons
rc3 - street of fire
rc4 - skytram station
bar_rc - typhoon
rc5 - central towers
rcboss1 - crystal palace east
rcboss2 - crystal palace west
kpcut7 - end sequence