At ANY opening screen/menu, type in :

iamcheater - (it''''s listed twice, so if once doesn''''t work, type it in twice.)
You''''ll hear a click if entered correctly

allitems - gives you all weapons with full ammo

resurrect - same as what zombie was in the demo, brings you back to life

goodhealth - gives you good health

nohits - player doesn''''t take hits

killthemall - kill all the enemies, but includes hostages too, beware!

funnyhead - Big heads, great for snipin!

gamedone - successfully completes current mission

gamefail - current mission ends in failure

openalldoor - opens all the doors

showtheend - I believe this shows the ending movie for the game. Use at ya own risc.

laracroft - heh.

enemyf - shows enemy in front of you.

enemyb - shows enemy behind you (so you can see where/what they are doing).

playercoords - your coordinates in the game.

debugdrawvolumes - no idea what this does.

debugdrawwire - wireframe mode

quickload - from the VERY 1st screen, I tried typing in iamcheater and then quickload, and I think the purpose of this is a quick random mission. I was put on the ship.