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DOOM 3 Hints

How do I open the hazard door in Monorail Access?

  • 1 of 9: It's been sealed due to high toxicity levels. You'll need to figure out how to lower those levels first.
  • 2 of 9: Find the unlocked door in Monorail Access and use it to pass through a few areas and eventually reach the Central Pipes Junction.
  • 3 of 9: In one corner of this area is another hazard door that's sealed due to high toxicity levels.
  • 4 of 9: Soon after you go through that hazard door, you'll encounter your first cherub creatures. Kill those baby-faced freaks!
  • 5 of 9: Keep going until you get to the main part of Underground Hazard, where you're required to fight a most titanic battle before you can proceed.
  • 6 of 9: When you come to a lift further on, save your game before you take it up to Main Environment Control. The toxic gas is so out of control in that area that it will continually damage you until you fix it.
  • 7 of 9: You do that by running along the walkway and clicking on the "Cycle Vent" buttons on the Environmental Control consoles.
  • 8 of 9: Soon after you hit all three, the air will clear and the doors in Monorail Access will be open.
  • 9 of 9: To get back there, go up the stairs and through the door at the other end of the Main Environment Control area.