Type in these cheat codes:

lapostal (all weapons, replenishes health)
laredlite (enables/disables a mode which makes all guys stop)
lapogo (you can step up any distance)
larandy (weapon supercharge)
laimlame (invincibilty)
lacds (all map, including secret areas)
labug (allows you to squeeze between any space)
laskip (goes to next mission)

The follwoing codes bring you to the respective mission:

lasecbase
latalay
lasewers
latestbase
lagromas
ladtention
laramshed
larobotics
lanarshada
lajabship
laimpcity
lafuelstat
laexecutor
laarc