MAP11: The Grotto (Community Chest 4)

MAP11: The Grotto is the eleventh map of Community Chest 4. It was designed by Chrisbo Sonnekins (Christoph) and Josh Sealy (Joshy), and uses "Grotto," a music track composed by Stuart Rynn (Forty-Two) specifically for this map.

Essentials
Just like the previous map, The Grotto is packed full of monsters - more than 550 of them on Ultra-Violence and above. Fortunately, The Grotto is also a massive map, resulting in a more spaced-out distribution of enemies. Figuring out where to go, on the other hand, can be a challenge - especially with two cyberdemons (four barons of Hell on Hey, not too rough and lower) that you have to dodge around to progress the level.

The map is divided into two halves - the southern half contains the red skull key, blue keycard and blue skull key. The northern half contains the yellow keycard, yellow skull key and red keycard. All six keys are required to exit. The open and connected design of this level allows for many routes to collect the six keys, so the walkthrough below is only a suggested route that aims to minimise the threat from certain traps.

Start and Red Skull Key

You begin on a walkway between two rectangular nukage pits. Watch for fire from shotgun guys and imps in the silver structure in the southeast. Head south until you drop into a dirt pit with a chainsaw and up to three demons. Take them out and go through the door in the west. You will enter a UAC base with green and silver STAR walls and be attacked by a large number of zombiemen, shotgun guys and imps. Be wary of the imps on a platform to the right of the door. Ignore the staircases in this area for now and head onto the grey-floored area for now.

Head down a short flight of steps into a grey T-junction with a "radiation" sign on the wall. Watch for an imp to the left. At the fork, go right (south). Turn the corner and take out another imp. As you walk through the light beam, the door ahead will automatically open, revealing another imp. Take it out and continue forward into a blue hall with a Hell knight. Kill the shotgun guys waiting in ambush around the doorway, then take the chaingun and boxes of ammo that it was protecting. Use the switch in the southeast to deactivate the force field in the door, then head in and kill the two shotgun guys and chaingunner in this computer room. Continue south into a control room. There are two spectres, a demon, four shotgun guys and a chaingunner behind the central computer panel. Flip the switch in the south to raise the bars to the red skull key platform.

Backtrack to the T-junction. This time, go north. Again, when you step into the light beam, the door automatically opens and you have an imp to kill. Follow the staircase down and watch for an arachnotron in the corner. Grab the rocket launcher from here. Head further south and kill the Hell knight in the corridor. At the end of this corridor, you will be in a stone platform in the northwest of a darkened cave. Climb up the stone steps, then follow the curve of the eastern wall of the cave until you reach the southeast of the cave. From there, a curving rock bridge extends to the east. Follow this bridge to the red skull key structure. As you approach the structure, up to four pain elementals will begin teleporting in - no big deal yet. When you pick up the red skull key, a larger teleport trap activates, causing up to 12 spectres to teleport to either side of the rock bridge. Chaingunners will appear in the control room in the north. On Ultra-Violence and above, a revenant and four cacodemons will also spawn on top of a pillar in the cave. Drop off the bridge to the south, then use the rock steps in the east to climb back up onto the east side of the cave. If you can verify that you're far enough from the spectres, soften them up with rockets. Quickly move along the steps and head to the northeast of the cave.

Blue Keycard

At the northeast of the cave, you will notice a brown stone passage. Head up it and watch for up to three mancubi along the steps. At the fork, go right (east). You will be confronted by up to five revenants. Continue along to a rectangular brick area with a nasty crossfire - up to eighteen shotgun guys in ridges in the north and east, six cacodemons, three demons two revenants in cages and four chaingunners in alcoves in the west. Rush to grab the blur artifact in the water so that the monsters start missing shots, hopefully sparking some monster infighting and taking the pressure of you. Your rocket launcher will help with clustered enemies. After that, it is just a simple matter of using the ladders to climb to the top level of the brick structure.

At the top of the brick structure, head northeast into a chamber with the blue keycard on top of a fountain. Flip the switch in the back of this chamber twice to raise a step to the fountain. Grab the blue keycard from the fountain. If you are playing on Hurt me plenty and above, you'll hear a cyberdemon waking up. Prepare yourself for some serious evasion and crowd control.

Blue Skull Key

Head back into to the brown rock tunnel and proceed north at the fork. The northern part of the level has opened up, revealing two cyberdemons in alcoves (four barons of Hell of Hey, not too rough and below). Revenants, demons, mancubi, cacodemons - you name it, it's probably somewhere in this new northern area taking potshots at you. For now, you don't have much ammo, so just try to pull the cyberdemons out of their alcoves - you'll need to head in there later to complete the second half of the level.

Quickly make a dash to the west to the starting area and open the red skull metal door in the wall. Kill the four imps and four shotgun guys ahead, then grab the super shotgun and backpack. At the junction, watch for imps on both sides and chaingunners on the left (south). Head right (north), then left (west) into a grey passageway. Watch for a demon ambush from behind and another demon further up.

You will now be in the entrance of an angular computer room with five imps and four demons. Shotgun guys and zombiemen will shoot at you from behind the bars in the northwest. The real danger in here, however, are the barrels - a stray bullet or two could detonate them. However, these can also be sued to your advantage. Carefully set off chain reactions to clean out the floor, then focus your fire on the former humans.

Climb up the stairs and head right (northeast). you don't have to worry about the enemies in the north, as a window separates you from them and blocks their vision. In the dark grey wall area, drop down to the southeast with the blue skull key, take it and climb the steps back up (these steps were raised by flipping the switch to collect the blue keycard). This allows you to avoid being stuck in the midst of a large teleport trap (up to 32 imps, 16 demons 3 mancubi, two Hell knights and two barons of Hell) and clean out the monsters from an elevated position.

After baiting one massive sequence of monster infighting, drop back down and collect the megaarmor, as well as health and ammo from the surrounding rooms. Open the blue skull bars in the south to exit. Remember, you are now back in cyberdemon territory, so act fast!

Raising the bridge to the Red Keycard

Back out in cyberdemon territory, lure one cyberdemon out of the left cyberdemon alcove. Head around it and enter the left cyberdemon alcove. Head up the steps and make a right turn into a rock alcove, which contains a chaingunner. Continue up another flight of steps, then run across the water into a short rock passage that opens up into a brown-walled base. Watch for a spectre near the doorway, a shotgun guy and up to four imps behind some windows. Proceed north, then turn the corner. Watch for an arch-vile ambush from behind, then open the door in the arch-vile's alcove. This takes you to the corner where the imps were. Head south to find a switch. Flip it, then rush back to the corner to find that the door in the west has temporarily opened.

Go through this door and kill the revenant ahead on the steps ahead. Climb up the steps to a control room with two demons and a baron of Hell. Kill them and flip the switch in the south to raise a T-shaped platform in the southwest, which will be used to access the red keycard later.

Backtrack and jump back down to the floor of the grotto via the waterfall, which makes it harder for the cyberdemons to hit you.

Yellow Keycard

Now, head into the eastern cyberdemon alcove. Head up the steps and kill the revenant on the platform. Continue east, climb up the stone steps and go east to a door. You will enter a corridor with triangular archways. Two demons and one chaingunner will attack you. Continue forward and turn the corner, facing two more demons and a Hell knight. From now on, watch for chaingunners on either side of the triangular archways. Head north, turn another corner and take out a demon, a baron of Hell and a mancubus. Flip the switch in the north of one of the northern corridor segments to unblock blast doors to the central room of this area. Enter any door into the central room of this area.

This central room contains eight shotgun guys and two imps, but the presence of an invulnerability and a berserk pack are a hint that something bigger is incoming. Flip the switch in the west. As you approach the switch, blast doors lower at all the doorways, locking you in. 24 imps, 16 demons and four Hell knights teleport into the room. Grab the invulnerability and berserk pack and get to work on these monsters. After about 30 seconds, the blast doors will open and you can leave. Use the northern doors to leave.

Turn the corner and ignore the door in the southwest. Instead, lower the large blast door in the triangular doorway in the north to access a grey corridor. Your first opposition is a pair of shotgun guys, a chaingunner and a Hell knight. Imps and shotgun guys will take potshots from the windows high on the left (western) wall. As you cross the first grey archway, watch for two chaingunners in ambush positions. As you head north, you will reach a metal-floored circular corridor. Along the way, watch for demons along the circular walkway and some imps on a ledge in the east. As you continue to the north of the corridor, the walls in the north open up, revealing a large sludge cave. Up to three cacodemons and two pain elementals will rush out, and a revenant will teleport into the north of the walkway, almost exactly at the trigger line. Some imps will also attack from a notch in the wall in the west. Clean house, then run across the pillars to the north to reach the yellow keycard.

Yellow Skull Key

'''Warning: This segment contains virtually guaranteed damage. You should only take it on when you have sufficient health.'''

Continue along the circular walkway counter-clockwise. Clean up any enemies left here. Continue forward into a room with a grey and brown staircase. Watch for two shotgun guys, four imps on the platform. As you enter the room, watch for a Hell knight and a spectre in ambush positions near the entrance archway. As you continue forward, a spectre and two cacodemons will attack from a corridor to the north. Head into the corridor where the cacodemons came from and ride the platform up.

This next grey brick area contains three zombiemen, two shotgun guys, a chaingunner and a revenant. Clear them out and head for the blue skull door in the north, with two imps in front of the door and a chaingunner to the left. Open the door and head into a cross-shaped outdoor area. There is arachnotron directly ahead and a mancubus in each of the western and eastern arms. Walk forward, and the floor sinks slightly, preventing you from accessing the blue skull door. A switch is revealed in the northern arm. Flip this switch, and the cross-shaped area lowers even more, placing you in a massive crossfire between 12 shotgun guys and three chaingunners.

Open either yellow skull door in the south and kill the two imps in front of the door. Climb up the steps and return to the grey brick room before the blue skull door.

Red Keycard

Take the elevator in the west down one floor to a grey walkway overlooking a long, thin. Watch for four arachnotrons in the corner, as well as cacodemons, imps, shotgun guys and revenants taking shots from the cave area. Open the door in the south of the walkway. Watch for a mancubus, two Hell knights and some imps, as well as continued fire from the enemies in the cave area. Kill them, then jump onto the T-shaped platform. Clear out the opposition and head onto the ledge in the cave. Head north. Follow it around all the way to the red keycard and pick it up.

When you pick up the red keycard, the ledge it is on lowers to the water. Six spectres, six cacodemons and an arch-vile will teleport into the cave. Head southwest along the water, around the rock pillar, and make a beeline for the metal pad with a red circle in the south. This will teleport you back up to the west side of the T-shaped platform.

Exit

Now, with all six keys, backtrack clockwise to the elevator and ride it up to the grey brick room south of the yellow skull key area. Head to the door with red, blue and yellow stripes in the south of the room. Open it and immediately turn around - the forcefield blocking the hole in the pillar behind will deactivate, releasing 11 demons and an arch-vile. You need to head into the room where they came from to restore the power and allow the ending elevator to operate.

Head out through the door with red, blue and yellow stripes. Kill the mancubus in front of you. Ahead is a metal structure on a green platform. Ride the platform up to this structure and flip the switch in the middle of it. The platform you are on will start rising. Shortly after, the map will end.

Secrets

 * 1) At the start, head through the brown corridor on the right with blue floors. As you ascend the steps, look to the right for a piece of damaged wall. Open it and climb the steps for a partial invisibility. (sector 927)
 * 2) South of the starting point is a depression with a chainsaw. Open the door near the chainsaw and enter the next room with staircases leading up. Ignore the staircases and look towards the walls that have UAC written on them. One is colored differently; open it for four backpacks. (sector 590)
 * 3) Just opposite of Secret #2, open the wall that has a radiation symbol on it for a soul sphere. (sector 732)
 * 4) Go south of Secret #3 into the room with the force field. Enter the elevator and take it down one level, then open the northern door. If you look real closely at the northern rocky wall, you will notice some red parts in a section that doesn't have the bottom "lip" like the rest of it. Press on the wall to lower it and follow the red path down to a room (sector 304) with an armor and energy cells.
 * 5) In Secret #4, an arch-vile quickly teleports into the room, and then out into the rocky cavern. To reach the BFG9000 on the rocky pillar, you need to lure the arch-vile into attacking you while he is out into the cavern, and perform a well-timed arch-vile jump to the pillar. (sector 747)
 * 6) Take the stairs (near secret #2) up north from the grotto with the red key (and secrets #3 and #4) into the brown-floored hallway and go west. You will notice some broken bars on the floor, which you can use as stairs to climb through the window into a darkened room with ammo, a berserk pack, a megaarmor, spectres, and chaingunners. (sector 503)
 * 7) Use the red skull switch at the western section of the map to open the nearby door, then circle around to go through the door. At the top of the steps, open the door you see and go around the blue column to get a soul sphere. (sector 522) Mind the damaging floor.
 * 8) Head up the stairs straight north from Secret #7 into a blue-floored hallway. When it bends a bit, veer off to the right down the steps to a computer room with barrels, imps, and demons. There are several terminals on both sides of the stairs in this room. On the left side of the staircase, press the computer panel in the middle and you will open a secret compartment (sector 83) behind you. Quickly get the invulnerability inside.
 * 9) In the eastern portion of the map with a corridor surrounding a blue-floored central square room (where you flip the switch to unblock the yellow keycard), follow the corridor to the northwest, then exit through the UAC door in the southwest. You will be on a higher ledge in the grotto. Head south along this ledge until you find a semi-circular ledge with a passageway, embedded in a vine-covered brown wall ahead. Hop onto that ledge and enter the passageway in the back, all the way into the darkened area. You will be dropped into a darkened channel, whose current will push you into a small cove with a revenant, a chaingunner, a plasma gun, an energy cell pack, and a box of rockets. (sector 741). To leave this cove, head into the darkened alcove in the south, where the current will push you back out into the main level.
 * 10) In the large room with the switch that opens the bars to the yellow keycard (the room is on the eastern part of the map), open the wall opposite of the switch to find some imps, energy cell packs, and a plasma gun. (sector 264)
 * 11) Inside of the cave with the yellow keycard, jump onto the ledge that has imps on it. From there, follow the ledge into a tiny passage where you can get a medikit and an energy cell pack. (sector 1880)

Current records
The records for the map at the Doom Speed Demo Archive are:

The data was last verified in its entirety on January 13, 2022.

Player spawns
This level contains five spawn points:
 * 1) facing south-west. (thing 4)
 * 2) facing north-west. (thing 5)
 * 3) facing east. (thing 6)
 * 4) facing south-west. (thing 7)
 * 5) facing east. (thing 8)

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

Technical information
Simulated "power-on" of lights

In the room north of the exit elevator, after opening the door that requires all six keys, the forcefield opposite that door de-activates and monsters are released from the room beyond the forcefield. The player must switch the switch in this room to "restore power", and the lights in the room turn on fairly realistically. The exit elevator will not work unless this switch is turned on.

In this map, this is accomplished with a voodoo doll in a control carrying sector. It is blocked by an obstacle. Around the central pillar in this room is a deep narrow pit (sector 1123). However, this pit is also joined to a control sector outside the playing area, which is adjacent to a control sector with light level 160 (sector 269). When the switch in this room is flipped, it raises the obstacle in the voodoo doll's control sector. This causes the voodoo doll to be scrolled across several light-controlling trigger lines in rapid succession, with the following effects:


 * The pit sector reads the brightness level of 160 from the adjacent control sector and changes its own brightness to 160.
 * After a small delay, the main room reads the brightness level of 160 from the adjacent pit and changes its own brightness to 160.
 * The windowsills read the brightness level of 160 from the adjacent main room and change their brightness to 160.
 * The light strips in the room change brightness to 255.
 * The pit sector changes brightness to 255.
 * The light strips in the room begin blinking.

This sequence of events gives a good simulation of an fluorescent light first dimly glowing when switched on before glowing brightly, as well as the delay in delivering (full) power to all peripherals after restoring power in what is presumed to be a large base.

At the end of this sequence, the voodoo doll is before a second obstacle, beyond which are the triggers for the exit sequence. If the switch is not flipped, the voodoo doll will not be in position behind this obstacle for the exit sequence, and the exit switch will not seem to work.

Delayed Exit

In the exit elevator, when the switch is flipped, the map does not end immediately. Instead, the elevator begins to rise for a short while before the level ends. This also exploits the voodoo doll in the carrying sector.

Both the exit elevator platform (sector 928) and switch block (sector 903) are joined to control sectors outside the map. Both sectors share tag 40. Each of these control sectors is adjacent to a third control sector (sector 889), with ceiling and floor at a significantly higher 1024 units.

When the switch in the exit elevator is pressed, all it does is to (temporarily) lower the second obstacle in the control sectors. If the sequence involving "restoring power" was completed, the voodoo doll continues to be scrolled across two lines, one 16 units away from the obstacle with Floor Generic: Walkover Once, Floor Raise to Highest Adjacent Floor (linedef 10724), and one 376 units away with Walkover Exit (linedef 1519). Thus, the player will ride the exit elevator up for a short while before the map actually ends.

Inspiration and development
The up and down elevator switch textures in this level were put together for it by project leader Eric Baker (The Green Herring) during compilation. The original submission featured regular switches, where the directions they would cause the elevators to go were marked by the handles' orientations.

Trivia
There is a switch in Secret #4 that lowers Secret #5 in the underground cavern, for about five seconds. However, at the very beginning of the game, the switch is closed off well before you are able to reach the secret. This is because the same arch-vile that is supposed to teleport into Secret #4 is in a dummy sector where the first linedef he crosses closes off the switch for good. Therefore, you are only able to access this switch if you are playing in mode.