MAP07: Frustration (Memento Mori II)

MAP07: Frustration is the seventh level of Memento Mori II. It was designed by David Kuykendall and uses the music track "Midnight Call" by Mark Klem. It contains a separate area for multiplayer competition. It is infamous for featuring a door that does not usually open all the way, forcing the player to use it repeatedly until it opens enough to allow them through.

Mission briefing
According to both the text file and the Infopack:


 * Finally you fight and frag your way out of hell, a sewer tunnel looms before you, light shines at the end. Salvation!  You have beaten them!  Not too hard you think to yourself, a cakewalk compared to last time...  Well, time to go home.  Humming to yourself you sling your shotgun over your shoulder you make your way to the exit, only to find that it is blocked!
 * Well dammit, must be a way around...how bout [sic] this ladder...?
 * Hmmm, maybe your [sic] not done yet...

Essentials
This level has a large amount of traps (both of the monster closet and teleport varieties) that trigger without warning, so use caution even when re-visiting earlier areas.

Yellow Key and Yellow Door

From the start, turn to your right and head up the ladder to a door. Open the door and proceed ahead.

In this piped-walled hallway are a number of shotgun guys. Clear them out, then proceed to the door in the west. Open it to reveal a small room with plenty of supplies. However, be careful of the imp and revenant (not on Hey, not too rough and below) in this room. Collect the two shotguns, two chainguns, chainsaw, armor and stimpacks (if needed) and head back out.

Next, proceed to the east side of the hallway, where there are two small doors facing a large door. Open the large door and immediately backpedal to the north. All three doors will open, and you will be wedged between an imp and a chaingunner (on Hey, not too rough and below), or a Hell knight and two chaingunners (Hurt me plenty and above). A number of demons will also begin teleporting into the corridor. Go through the big door and collect the yellow key, but be wary of the imps in cages on either side.

Go back through the door in the north, and drop back down the ladder into the sewers. Go through the small door in the northeast. To the left, you can see a soul sphere behind a jammed door, but be careful of the imp and chaingunner nearby. The next brown door ahead is the infamous "frustrating door" that probably gives the level its name. When you open it, it seems to jam at a random height. However, it isn't exactly random - the height at which the door will jam actually follows the movement of a crusher. Repeatedly open and close the door to see whether the height of the "jam" currently is, and time your opening of the door to get through.

In this next hallway, kill any shotgun guys and imps you see. Go to the end of the corridor and open the door to reach a T-junction. Open the yellow door in the south and go down the hallway. As you approach the door ahead, it will suddenly open, revealing up to three imps and on Hurt me plenty and above, a revenant. Back up and hold them at bay with your shotgun.

This next room has a central pillar with a slimefall. As you approach the computer panel in the south, the door in the east opens, revealing an imp (Hey, not too rough and below) or a revenant (Hurt me plenty and above). Once you've dealt with it, press use on the computer panel. The slimefall within the pillar should shrink to a thin stream. This opens up another area in the north.

You will be back in the hallway just after the "frustrating door". A trap will open in front of you with up to three imps and a revenant. Dispose of them and head back through the "frustrating door." Back in the dark corridor, immediately look right (towards the west) - up to two chaingunners have been teleported here, and lie in ambush.

Go through the small door, and return to the sewers.

Red Key and Red Doors

Go back up the ladder, open the door ahead, and return to the part of the hallway in the east with three doors. Open the big door ahead (watch for imps from the two small doors), and grab the super shotgun. This room is chock-full of opposition, with your biggest threat being a cacodemon (Hey, not too rough and below) or a pain elemental (Hurt me plenty and above) that appears from the slime. Grab extra shotgun shells from the southeast corner, then use your chaingun to take out the soft targets and your super shotgun to take out the flying one.

Once the room is relatively clear, head to the northwest corner of the room and collect the red key from behind a pillar. Head back out the stairs and backtrack to the sewers.

Go back through the door in the northeast, through the "frustrating door", down the hallway back to the T-junction. This time, go through the red door. This large room has a catwalk around a slime pool. Kill the imps ahead, and go around the catwalk. As you reach the steps in the west, equip your chaingun and try to snipe the two or three chaingunners that you can see through the windows in this room. Head through the door in the southwest, and kill the imp on either side.

Head through the door ahead, and you will be in a long corridor. Watch for a shotgun guy in the east, and kill him. Proceed to the eastern end of the corridor to collect your hard-earned soul sphere. Open the nearby small door and go through it.

Blue Key

You are now in a different part of the sewers. This time, you are going to face much stiffer opposition - mancubi. Use your super shotgun to puncture them. Follow the grey metal path to a T-junction. Watch for an imp waiting in ambush, then go through the western door (the eastern door is a fake - it's just a wall with a door texture).

In this set of corridors, run forward until you hear a revenant wake up (two on Ultra-Violence and above), then back up. Use your super shotgun to drop them quickly before they overwhelm you. Walk into the corridor which the revenants came from, and you will see two doors and the blue key through a window. None of the doors work. Exit the corridor and leave via the door you came in.

Walking into the revenants' corridor opened a metal panel northeast of the T-junction in the sewers. Enter the hallway and collect the berserk pack at its end. Feel free to use it on the demon in the trap ahead. Look for a nearby switch and flip it, which opens up the door opposite the switch.

In this next dark room, kill the imps. Flip the switch in the north wall of this room. As you approach the west of this room, the west wall opens up to reveal a Hell knight. Dispose of it, then flip the switch in its alcove to open the door that you used to enter this dark room.

On your way out, look for an imp to the right in a newly-opened trap. Leave this area and return to the sewers.

Next, look for a newly-opened doorway northwest of the T-junction, flanked by blue lights. Head inside and lure the Hell knight (Hurt me plenty and above) out. Collect the computer map it was guarding and flip the nearby switch. Head back out the doorway you came in.

Backtrack to the T-junction, and go through the western door again. Return to the corridor with the pair of doors near the blue key. One door should be open now. Go through this door, collect the blue key, and follow the passageway around to another door. Open it, and return to the corridor.

Exit

Collecting the blue key has triggered a large number of traps of various types. You will now have to fight your way through previously-visited areas to get to the exit.

Return to the sewers. A trap south of the T-junction will have opened with a demon; another one opened west of it with another demon (Hey, not too rough and below) or a mancubus (Hurt me plenty and above). Kill them, then proceed through the doorway northwest of the T-junction, flanked by blue lights. This time, continue down the corridor, and open the large brown door nearby.

The two cages on either side have somehow "refreshed" with more imps. Kill them and proceed through the door ahead, back into the room with a catwalk around a slime pool. Prepare your heaviest weapon and prepare for mayhem.

Numerous traps, both monster closets and teleport traps have filled this northern part of the map with a large number of enemies! You will have to fight your way back to the "frustrating door" facing a large number of imps, chaingunners and up two revenants and two Hell knights roaming the corridors. This will be a tough battle - you need to try to cause some monster infighting to save your ammo and take the pressure off you. get through the "frustrating door", and head back into the starting sewers.

Climb back up the ladder into the hallway. Watch for imps that have re-populated the hallway. Open the big door in the east again, and deal with a newly-teleported Hell knight. Go through the door ahead into the room where you picked up the red key. You only need to worry about a newly teleported cacodemon (Hurt me plenty and below) or pain elemental (Ultra-Violence and above) from the slime, as well as two chaingunners that have appeared in the trap in the southeast.

Go through the corridor in the south of this room. Kill the revenant ahead. Pick up the rocket launcher on the floor, and switch to another weapon. Press use on the bars blocking the switch ahead, and immediately run backwards to the corridor before you get wedged between a Hell knight and a wall.

Return to the alcove flip the switch, and a nearby gate will open. Deal with the chaingunner or two, and step out into the final stretch of the sewers.

Your last opposition is up to four mancubi that roam this last stretch of the sewers. Use your rockets wisely to deal with them. Head to the northwest corner, where the exit door is.

Open the exit door and climb up the ladder to exit the level.

Secrets

 * 1) When you open the door leading to the yellow keycard, another set of doors will open behind you to reveal two (one on easy skill levels) chaingunners. Enter either one of the compartments they came from, and press on the wall with the lightning bolt on it. It will open to reveal a blue armor. (sector 497)
 * 2) In secret #1, press on the western wall with the lightning bolt on it to find a medikit (sector 531).
 * 3) In the room south of the hallway behind the yellow door, after thinning out the slime flow, enter the door to the east you just opened approaching the computer terminal. Press on either wall with a lightning bolt on it to open two alcoves with a chaingunner each (only one on easy skills). The southern alcove has a wall with a lightning bolt on it, unlike the northern one; press on it to discover a medikit. (sector 291)
 * 4) To access the blue keycard, you must find a switch in a dark, metal room, opening a door leading to a hallway with another switch that enables access to the keycard. In the aforementioned metal room that is in the southwest of the berserk pack, press on the wall with the lightning bolt on it to the south to find a blue armor (sector 543).
 * 5) As you exit the blue keycard room, you will find yet another wall with a lightning bolt on it; press on this one to find a box of shotgun shells. (sector 559)

Bugs
Linedef 367, which is part of the invisible "crusher line" near the start of the level that triggers the "frustrating action" of the frustrating door, erroneously does not have linedef type 141 (W1 Start Crusher Slow, Silent). Hence, once can avoid the "frustrating action" of the door by carefully walking on the southern (right) brown ledge next to the central metal path.

Current records
The Compet-N records for the map are:

The data was last verified in its entirety on May 11, 2014.

Things
This level contains the following numbers of things per skill level:

Technical information
The "frustrating" door works by exploiting the property of doors to open to four units below the lowest adjacent ceiling.

The door (sector 177) actually consists of two merged sectors. One is the door itself, the other is a zero-width sector outside of the boundary of the map. This zero-width sector is adjacent to another sector outside the map, sector 180. Hence, sector 180 would also count as an adjacent ceiling for the purposes of the door.

When the player starts the map, he is likely to cross one of linedefs 358, 362, 364, 369, 371 and 373. These lines all have special 141 (W1 Crusher Start Slow, Silent) with tag 3. Sector 180 also has tag 3 and is adjacent to a sector with ceiling 96 and floor 8 (sector 179), so it begins oscillating between heights of 16 and 96 units.

The neighbouring sectors to the actual door that are within the level geometry (178, 175, 174) have ceilings of 96 units. Thus, since sector 180 is oscillating between heights of 16 and 96 units, it is very likely to be considered the lowest adjacent ceiling for the purposes of the door's operation. Thus, when the player opens the door, the lowest adjacent ceiling is calculated by reference to sector 180. Hence, the door will raise itself to whatever height the ceiling of sector 180 is at that time, minus four units, giving the appearance that the door has jammed at a random height.