MAP20: Silures (Eternal Doom)
From DoomWiki.org
MAP20: Silures is the twentieth level of Eternal Doom and was designed by Bob Evans. This level can be quite frustrating, remember: objects can be switches too!
Strategy
Walkthrough
You start off on a blue teleport pad. Kill the Imps surrounding the water courtyard. Facing the box of rockets through the bars, turn around and hit a skull switch, lowering you into the water. Head into either tunnel and activate the wall at the end to open it. To your left is a fountain with a Super shotgun on a post. I don't know how to get that. Three-eyed skull doors look like they lead into a central area, but they don't actually open so don't worry about them. Watch out for Chaingunners and Skulls that pop out of the stone supports. Down the left side (fountain side), there is a corpse and some cobwebs. Go in here to pick up a shotgun and some ammo. Come back out.
Right after this, on the left, there is a room with green slimier walls (and a Chaingunner). There is a switch in this room. Hit it, and look back towards the Super shotgun fountain. A pillar has popped up in a dead end hallway with a switch on it. Hit that switch and a secret door will open to the right with some Spectres in it, plus another switch tucked around the corner. (Shortcut: you can actually open this door simply by activating the wall even without hitting the first switch.) Hit this second switch and a secret door will open in the other dead end hallway, to the right of where you came in.
Before going through, finish collecting some more goodies down the right side of the water area. Head down the right side and you'll hear an elevator drop. This is around the back, so run around back to get there in time. Collect the ammo and health and ride the elevator up. A switch lowers it back down again, but one behind you lowers the next wall to your left. Hit that and head over to pick up a few more goodies. You can get the chaingunners weapons where the backpack is by activating the wall in just the right place. Also along the right side is a small area with a couple Cacodemons in it. There's a chainsaw in there.
Ok, time for the next part. Head into the dead end hallway door to see a statue and a couple cobwebs. A narrow hallway goes off to the left. Activate the statue to open a secret door on the right and kill a few chaingunners. Take a look at the yellow key if you want. There is also a switch in here... I don't know what it does yet. Go back out to the statue room and make your way down the narrow hallway, killing a Revenant hiding around the corner as you enter. Make your way through a series of switches to cross through the support beams of the water area. At the last switch, make a running jump to enter a room with some 5 demon head switches. The 1st and 5th close the door behind you. The 2nd opens the door--but don't hit it yet. First you have to hit the 3rd middle switch to lower the elevator outside--you can't jump across. So hit the 3rd switch, then the 2nd, and then run across. There is a crystal ball here.
...Scene missing...
Start from the room with the open hallway and the mud on either side (with the candles at the end). Exit this area and take a right, back to the grey rock cave filled with water, where you first came into this area and fought a Hell Knight or two. A hard-to-see narrow stairway on the left leads up into a stone area with a couple of Demons in it. At the end of this room where a couple Demons pop up is a red switch. Hit that switch... I don't know what it does though.
On your way back, you can get a plasma gun. There's two skull switches right near the top of the stairs (one is further on and around the corner). Hit the furthest one and a wooden room will open up near the top of the stairs. Enter that room and fight a Hell Knight. The rear wall opens up onto the grand hallway (with the trees outside). Don't exit yet, instead go back and hit the closest switch to lower the window ledge in the grand hallway. Run back through the wooden room before the ledge goes back up, through the automatic door, and straight across before the ledge goes back up to get to the outside treed area. Pick up the plasma gun in the corner. There is also a dead tree. Activate the dead tree to open a secret door behind it.
Go through the hallway to get back to the side of the mudroom. A Baron of Hell will appear and teleport around you, plus an Archvile will spawn on the main mud bridge hall thing. Kill them, and make sure you don't fall in the mud because you can't get out. Head on through the entranceway where the Baron spawned and the exit is right there, but blocked. Look around the corner to the right for a blue key switch. I hope you have the blue key! Hit that switch and step through the teleport to finish the level.
Yellow Key
Getting the yellow key is complicated, and all you get is a blue armor (at least I think that's all you get). Go back to the mud hall. There's two teleporters right before you go outside into the mud hall. Go in the one closest to the mud hall, and you will be transported into a water area. On either side is bars and an energy cell pack, and there's a teleporter in the middle. Don't go in this teleporter. Instead, turn around and notice the bulletholes in the rear wall of the teleporter you just came out of. Shoot that wall and a teleporter will open on the other side of the room. Go through that teleporter and you will teleport into the left cage. Go to the end of the cage and activate the demon head wall switch. This opens up another switch in the next room, so you have to be quick. On the left wall is another sort tablet-y switch. Open it to reveal a teleport and jump in.
You will teleport back to that stone room with the Demons in it. If you did it quick enough, there is a skull switch that is right in front of you. Hit that switch and quickly run to the rear of the stone room where a door has temporarily opened up. Head through (gaining a secret area bonus) and collect some rockets. Go through the waterway and vines and you are now in the yellow key room. A small stairway on the side leads up. Head to the rear and watch out for two Revenants. Around the corner is a switch. Hit that and the rear will open up. Head in and fight an Archvile. Once you have killed him, take a look at the statues. On the left side, one of the statues is missing. Activate this wall and a pillar will open up to reveal the final switch. Hit this switch to lower the yellow key and pick it up.
Head back out to the grand hallway (you can use the other teleporter near the mud hall, or use the plasma gun shortcut). Go in the three-eyed skull door (at this point you've been in here already I think). Ahead is a barrel and a disembowled corpse. At the right is the yellow key door. Activate it, and step up on the left hand yellow key marker to get onto it (it doesn't go down all the way, but the marker has a tiny bite taken out of it). The room has a pool with a blue armor in it, and some Chaingunners and Imps up around the sides. Once you've taken care of them, head to the rear right of the room. There is a strange looking wall texture right on the corner. Activate it to reveal a switch which lowers some stairs. Go up the stairs and collect the guns the chaingunner left behind, and jump down to get the blue armor.
The previous level is MAP19: Warheros (Eternal Doom)
The next level is MAP21: Fire and Stone (Eternal Doom)
