Level 19: House of Pain

Immediately upon starting, grab the Rocket Launcher, Armor, and Medikit, then defeat the Demon.

Step into the teleporter the Demon was guarding.

Turn right and proceed through the opening across from you, being mindful of Imps and Demons.

Follow the right-hand wall until you reach a large room filled with Lost Souls containing the Blue Key.

Defeat all Lost Souls and retrieve the Blue Key from the far end of the room.

Turn around and exit this room.

In the open area, turn right and enter the next opening.

Open the Blue Door at the far end of this room and pass through.

Open and go through the door at the far end of the next room, eliminating any Demons or Cacodemons.

Open the door to your left and proceed through, defeating any Demons.

Use your BFG (Plasma Rifle) to clear the room containing Zombiemen, Shotgun Guys, and Lost Souls.

After clearing the room, open the door at the far end and go through.

Defeat the Imps and Demons, then interact with the demon face symbol to open it like a door.

Inside, collect the Soulsphere and the Red Key from the lava pit, then exit the room.

Return to the small room and then exit it.

In the larger room, turn left and open the door, then go through.

Fall into the small pit across from you to acquire the BFG (Plasma Rifle).

Activate the switch to return to the floor above, then exit this room.

Back in the main area, open the door at the far end and proceed through.

Interact with the wall to your right; it will open like a door, so go through.

Collect the Medikits, Box of Rockets, and Energy Cell Pack, then return through the door.

Exit this area by opening the door to your right and going through.

Open the door to your right and proceed through.

Open the door at the far end of the next room and go through.

Open the Red Door to your left and enter.

Head left to find a door. As you approach it, a wall to your right will open, releasing Demons. Defeat them all.

To open the other door, face the tile next to the wall that opened. Step onto the tile and then step off to the RIGHT. This should open both doors; if not, experiment with the tile.

Once both doors are open, proceed through them.

Follow the hallway to an opening, eliminating any Imps in your path.

Enter the opening.

Turn right and defeat all Imps in front of you.

Go straight into the large room across from you.

Locate the platform above and an opening to your right. Enter the opening to reach the platform.

Defeat the Barons of Hell on the platform and grab the Yellow Key.

Drop down to the floor below.

Before opening the Yellow Door, notice a new opening to your right.

Defeat the Cacodemons and Imps and enter this new opening.

Collect all available health and ammo.

Pick up the Invincibility Sphere.

Exit this area and return to the room with the Yellow Door.

Open the Yellow Door at the far end of the room and go through.

Activate the exit switch.