When two alcoves are opened when you try to open the normal exit door.Also, open the wall with lamp in the bottom to get to the second room where there are a medikit, three health potions and 4 shotgun shells. ( sector 252) Grab three health bottles, a medikit, a plasma rifle and 4 shotgun shells. In the room of the sixth floor open the wall marked by metallic bars in the east.( sector 155) You can grab a couple of shotgun shells and a soulsphere inside. When you are at the bottom open a secret wall near the box of shells. There is a dark corner in the end of the balcony that moves up and down. In the third floor (by entering the fourth floor) walk through to the north balcony containing nine health potions.

After you have visited the second floor the platforms on the third floor will start moving up and down.Enter the blood pool to get to the Bad Dream contained in the same WAD. When you are in that niche open the yellow, then the red and finally the blue one. Use the arch-vile to cast the fire on you to be brought to the niche with yellow door you can see (it is recommended that you are invincible you have took invulnerability sphere). Come back to the fourth floor and enter the southern alcove in the next room (it can be closed depending of whether you have entered the balcony with mancubus or not).When you rise open the wall, then find and take the yellow key.

Two lifts in the north-western side are lowered along with that ones (and can only be activated from north-eastern side).

Activate two lifts in the north-eastern part of the room (that lead to the button) on the fifth floor.

Now the blue key is accessible in the fourth floor. It differs from other walls and requires the red key.

Being in that room notice the segment placed on the eastern part of the central structure.

In that much darker room grab the well noticeable red keycard. You will be teleported to the fifth floor. Open the secret wall in the south part of room.

Go to the second floor, enter the dark room.

Enter the blinking gates to beat this level. When you rise flip another switch to open that, in fact, real exit door. Flip the switch to lower a platform in right of you. Walk upstairs and try to open the 'fake' exit door. Get to the other side where a skull lever is placed that unlocks the last bars in the eighth floor.

Note and beware zombies in the cages and revenants that are revealed in all floors of the level. Just press the button in the next room of this floor to unlock the bars in the seventh floor. In the top press the button to unlock the bars in the sixth floor. In that room you can see a button in the alcove located in the north-eastern corner. In the fifth floor open the door before you. Killing several mancubi press the button in the end to unlock bars in the fifth floor. In the balcony where one mancubus is/was open another door. You could enter the door first and in this alcove (note that you can also visit this place without needing to unlock the bars) stand on the button indicated by two arrows to ease your task by killing one of three mancubis with crusher, however this can make it difficult to grab the medikit located right under that crusher. From the lift drop down on the stand to press the second button above that unlocks the fourth floor. In a room press the first button below to activate the lift in the middle. Find and press the button there to unlock bars in the third floor. You will be teleported to the structure of the fifth floor. Flip the switch, deal with knight/ baron, flip the switch to unlock the bars leading to the second floor. Walk around to get to the room where you can only peer through windows. Give 30 seconds while they are closed and return. The bars will automatically close as you try to enter the floor. There are also three optional keys in the level that are necessary just to get to the secret level. Entrances of each floor are indicated by a number on the floor and ceiling. You start on the rounded lift that is immediately lowered as a monster standing before you crosses the line to activate the lift. Sector numbers in boldface are secretsВ which count toward the end-of-level tally. Letters in italics refer to marked spots on the map.

Doom 3 map editor elevators