In the levels after Riddick leaves in his submarine and the base is set to self destruct, you will eventually reach a point where you crossed through water before. Go back into the water and find the point where you first dropped in. There is no ladder to climb back out. There is a secret box here. Swim to the upper right corner in the water and you will see a cross eyed fish.
After entering the lab with the mutants, shoot and kill the scientists there and cause chaos. After this you can hear one of them say "I'm not even suppose to be here today!" referring to Dante Hicks from Clerks.
To defeat the large monster in the wooden area, drop to the right immediately after you go into the pit. Let him charge at you until he is in the corner. Stun him with the pistol, then run back to where you started. There should be a flammable barrel nearby. Shoot it and try to catch him on fire. This deals significant damage, and you should only need several more pistol shots and a couple shotgun blasts to finish him off.
Note: This procedure requires editing a game file; creating a backup copy of the file before proceeding is recommended. With a text editor, edit the "config.cfg" file in the game directory. Change the value of the "con_enable" line to "1" to enable the console. Press ~ during game play to display the console. Enter sv_cheats 1 to enable cheat mode. After that, enter one of the following console commands to activate the corresponding cheat function.
CHEAT FUNCTION - CHEAT CODE God mode - god 999 health - health 999 All weapons and ammunition - impulse 101 Ignored by enemies - notarget No clipping mode - noclip
At any vending machine, press any button rapidly until a health canister will drop out. This can be done twice. However after this, a live grenade will come out and endanger you, unless you throw it back or run away
-Soldiers are a very tough enemy to fight at first. An easy way to defeat them is to get very close with the shotgun, usually touching them. However, if done on a long strip of land with no cover, you will not survive long. Try hitting them in the head with the pistol, or spray just above their head with the rifle while zoomed.
-When you get in the car after navigating the maze after the monster, you must engage two supers and a couple regular soldiers before you get out. Instead of getting out and losing a ton of health, close the window and start throwing grenades without standing up. This is an easy way to kill all the soldiers, or set them on fire.