Before you even read the next line, your ass is already DOOMed. You've plunged into the world of DOOM 3 and there's no turning back. Your only choice is to step into the next dark hall and hope you don't die.

There are no cuddly aliens on the planet Mars, only brutally leathal demons and hellspawn. Tucked away in every pitch-black crevice and corner is something lurking and waiting to kill you. Hiding is not an option for you, as you'll have to blast your way through the many massive levels of DOOM 3, struggling to stay alive. Hundreds of halls of darkness await, and every inch of darkness is longer and more daunting than a mile in the light. Get used to snuggling with your flashlight—it's your only vestige of hope. Well, maybe not your only. Thankfully, we're here break you from the stranglehold of fear.

Inside this DOOM 3 stratey guide, you'll find:

• Basics: All the tips and strategies you'll need to destroy the evil demon hellspawn! New to DOOM? Check here first.
• Enemies: Tactics to bring down the gnarliest of beasties and avoid their deadly grasp, with tactics for all nineteen species.
• DOOM 3 walkthrough: Every one of DOOM 3's levels, detailed and beaten. Find secret stashes of weapons and health, and be ready for the next batch of nasty enemies.
• Multiplayer: All the skills you need to beat your friends, with level specific details for DOOM 3 noobs.
• Secrets: Complete list of locker combos—never skip a locker again, and earn the BFG as early as possible!

Get the DOOM 3 Online Strategy Guide

During gameplay, hold LEFT TRIGGER and enter B, A, X, Y.

These are the Ultimate DOOM and DOOM 2 cheats which are only included with the Limited Edition Doom 3 game.

• All Keys, All Weapons, and Full Ammo: hold down LEFT TRIGGER and press A,B,A,B
• Berserk Mode: hold LEFT TRIGGER and press X,X,X,Y.
• End Level: hold down LEFT TRIGGER and press A,A,B,B.
• Chainsaw: hold down LEFT TRIGGER and press B,B,A,A.
• Weapons and Ammo: hold down LEFT TRIGGER and press B,B,B,B.
• GOD Mode: hold down LEFT TRIGGER and press A,A,A,A.
• Invisibility: hold down LEFT TRIGGER and press X,X,Y,Y.
• Light Amplification Goggles: hold down LEFT TRIGGER and press Y,Y,Y,X.
• Radiation Suit: hold down LEFT TRIGGER and press X,Y,Y,Y.
• Show All Map: hold down LEFT TRIGGER and press Y,Y,Y,Y.
• Temporary Invincibility: hold down LEFT TRIGGER and press X,X,X,X.
  Date Added: 1970-01-01

  Cheat: God Mode

  it works: 0% | it doesn't work: 0%

  During gameplay, hold LEFT TRIGGER and press X, Y, B, A to become invincible.

  Date Added: 1970-01-01

  Hint: Storage Locker Combos

  it works: 0% | it doesn't work: 0%

  #	COMBO	LEVEL	ITEMS
  001	396	Mars City	bullets
  003	483	Recycling 2	clips, grenades, plasma cell, security armor
  009	752	Alpha Labs 1	clip, grenades, large med kits, security armor
  013	586	Admin	clip, grenades, security armor, shells
  017	347	Infirmary	clip, large med kit, security armor, shells
  023	531	Mars City Underground	armor shards, large med kit, shells
  038	409	Alpha Labs 2	clip, grenades, security armor
  039	102	Alpha Labs 2	clips, security armor
  047	123	Alpha Labs 3	clips, grenades
  048	123	Alpha Labs 3	ammo belt, large med kit, plasma cell
  049	123	Alpha Labs 3	armor shards
  054	246	Communications	grenades, security armor
  054	142	Monorail	grenades, rockets, security armor
  063	972	EnPro Plant	plasma cell, plasma gun, small med kit
  064	651	Alpha Labs 4	armor shards, clip, plasma cell
  078	364	Monorail	clips, grenades, large med kits
  079	364	Monorail	clips, grenades, large med kits
  103	259	Delta Labs Level 2B	large med kit, plasma cells, shells
  104	579	Delta Labs Level 4	ammo belt, rockets, security armor
  112	538	Delta 2A	armor shards, cells, shotgun
  114	715	Delta 2A	backpack, clip, security armor
  116	972	Delta 2A	BFG cell, large med kit, plasma gun, security armor
  116	624	Delta 2B	bullets, plasma cell, shells
  117	624	Delta 2B	BFG cell, grenades, security armor
  213	371	Delta 2B	clip, plasma cells, shells
  21D	298	Delta 1	grenades, large med kit, rockets, security armor
  317	841	Delta 4	bullets, clips, large med kits, rockets, security armor
  386	836	Delta 3	ammo belt, bullets, clip, large med kits
  387	836	Delta 3	clip, grenades, large med kit, rockets, security armor
  452	571	CPU Complex	grenades, rocket launcher, rockets
  666	372	Delta 2B	imp, security armor
  669	468	CPU Complex	grenades, plasma cells, security armor

  Date Added: 1970-01-01

  Hint: Martian Buddy Locker Combos

  it works: 0% | it doesn't work: 0%

  #	COMBO	LEVEL	ITEMS
  001	0508	Administration	ammo belt, chaingun, security armor
  002	0508	Delta 2B	BFG, security armor

  Date Added: 1970-01-01

  Hint: Duck Hellfire

  it works: 0% | it doesn't work: 0%

  The projectiles thrown by the imp and hellknight can be ducked if you time it correctly (it will do no damage). Naturally, you want to do this against enemies on the same height as you, not on shots coming at diagonals.