At the main menu, highlight Extra Content then press R. Enter the
codes  at  the  keypad,  the nactivate/deactivate at the Extra Content
menu on the Select Mission screen.

     Note!  All Powers only unlock the powers you've already unlocked,
making it possible to use these powers on previous levels.

Result:                           Cheat code:
Unlimited Ammo                    978945
Use Less PSI power                456456
Take Less Damage                  548975
All Powers                        537893
No Head                           987978
Unlock Arcade Mode                05051979
Unlock Coop Mode                  07041979
Unlock Survival Mode              7734206
Unlock Dark Mode                  465486
Unlock Pitfall Mission            05120926
Unlock Panic Room Mission         76635766
Unlock Up And Over Mission        020615
Unlock Stop Lights Mission        945678
Unlock Gasoline Mission           9442662
Unlock Bottomless Pit Mission     154897  
Unlock TK Alley Mission           090702
Unlock Gear Gauntlet Mission      154684
Unlock Tip The Buddha Mission     428584
Unlock Psi Pool Mission           565485
Unlock Aura Pool Mission          659785
Unlock Bouncy Bouncy Mission      568789
Unlock Gnomotron Mission          456878
Unlock Training Nick Skin         564689
Unlock Urban Nick Skin            484646
Unlock Wasteland Nick Skin        975466
Unlock Stealth Nick Skin          456498
Unlock Suicide Sara Skin          678999
Unlock Sara Skin                  135488
Unlock Psi Sara Skin              468799
Unlock Wei Lu Skin                231324
Unlock Tranquility Wei Lu Skin    654654
Unlock Dragon Wei Lu Skin         978789
Unlock Barrett Skin               497878
Unlock Training Barret 1 Skin     196001
Unlock Training Barret 2 Skin     196002
Unlock Training Barret 3 Skin     196003
Unlock Training Barret 4 Skin     196004
Unlock Training Barret 5 Skin     196005
Unlock Training Barret 6 Skin     196006
Unlock General Skin               459797
Unlock Clown General Skin         431644
Unlock Jack Skin                  698798
Unlock Burned Soldier Skin        454566
Unlock Soldier Skin               365498
Unlock Dock Worker Skin           364654
Unlock Scorpion Skin              546546
Unlock Labcoat Skin               998789
Unlock Komiko Skin                978798
Unlock Tonya Skin                 136876
Unlock Jov Skin                   468987
Unlock Saranae Skin               65496873
Unlock Fetish Pyro Skin           231644
Unlock Bikini Pyro Skin           135454
Unlock Marlena Skin               489788
Unlock MP1 Skin                   321646
Unlock MP2 Skin                   698799
Unlock MP3 Skin                   654659