When you are down there, kill the enemies to you left, and hit the switch. Head right, and take the stairs up, and go left. Destroy the barrel and you sould kill some demons. Kill all the enemies in your way and open the next door. = E1M3: Toxin Refinery Weapons Availble Here: Chainsaw, Shotgun, Chaingun, Rocket Launcher = Start the level by opening the door and heading left. In the middle of the room, take the elevator down and hit the exit switch. Open the exit door, and kill all of the demons here. Passages will open, and enter them and head right down the stairs. Kill the demons here, and flip the switch on the other side of the room. Head straight and you should be brung down lower by and elevator. Go straight to skip the floor and if you get hurt from the slime, there are Medikits on the other side of the room. Kill the enemies here and head striaght and go up the stairs. Kill the enemies here, and enter the Red Door.

Now go to the other side of the room we haven't explored in the area we started in. In this little room, go to the right and grab the Red Key. When you are done here, go back inside and head up the stairs we see in front of us. On the other side of this room is a Chaingun, with a SoulSphere to get on the way. Go up the stairs and enter the opening which leads outside. Enter the left one (both ones lead to the same room, but this door leads to the secret faster). Now turn to your left or right and open the doors in the nearby alcove. In here is some armor, health, a backpack, and a switch. Check the walls for a gray rectangle and search it. = E1M2: Nuclear Plant Weapons Available Here: Shotgun, Chainsaw, Chaingun = From the start, exit your little alcove and go to your right and on this side of the room, turn left. No go back to the exit door, open it, and hit the switch to finish the level. Enter the passage it was blocking and take the Shotgun. Remember the platform the Imp was on? Well now it's been lowered. GO to the exit door, but go back to the zig zag room. Kill the Imp and grab the goodies if you want to. Get back into the zig zag room, and open the door to our right. Follow this little hallway and it will bring you outside with a Blue Armor on a slime pit. A secret door will open, and there are some goodies in there. Get across the zig zag floor, but before you open the door, search the walls to your right. Across from us on a platform is an Imp, and kill it. Enter the passage in there, and kill the zombieman in front of you. There's a bunch of Armor Bonuses in here, but the important part of this room is the northeast side of the room. Kill the zombiemen across from us and take ther ammo if you want. Kepp going straight (not from the power up room) and go into the alcove. There's a room to your left with power ups in them if you want them. Grab them if you want, and then head straight.

To the left and right of you are Health Bonuses. Episode 1 Walkthrough = E1M1: Hangar Weapons Available Here: Shotgun = You start in a big room with your Pistol.

Doom 3 walkthrough part 1