MAP11: Circle of Death (Doom II)

MAP11: Circle of Death (named " 'O' of Destruction!" on the automap) is the eleventh map of Doom II. It was designed by John Romero and uses the music track "The Healer Stalks". The automap name is a reference to the Hoe of Destruction in the Ultima series of games, of which Romero is a fan [src]. This map also introduces another new enemy, the arch-vile.

Walkthrough
Proceed along the walkway (A) to your right and take a right across the bridge into a rusty metal area. Climb the stairs and take out the arachnotrons and cacodemons that attack. Proceed up either staircase into the structure ahead of you. Once you pass through the doorway inside the structure, the first arch-vile of the game is released (B). Take cover behind either side of the door if needed. Once it's been killed, re-enter the room and pick up the blue keycard (C). Now return to the main area of the level.

Make your way along the walkway to the opposite end of the area and go through the blue door (D). Flip the switch to raise a ledge just outside (E). Continue through this room, up the small staircase, and along the newly risen ledge. Flip the satyr-faced switch and return to the main area once again. Continue along the walkway to the left about halfway, and across the newly created bridge to the red keycard (F).

Drop down into the slime to the northwest of the central circular walkway and head through the red door (G). Proceed through the hallway, towards the iron bars (which will automatically open), and up the stairs, arriving at a wooden skull switch. Flip it to lower a platform just outside. From the new platform, drop onto the cement walkway and continue along it, eventually dropping into a dark cave (H). Dispose of the flying enemies here and head through the brightly lit tunnel in the structure ahead. You should now be in a "E"-shaped watery room (I). Ride the lift in the upper prong of the "E" up to a switch. Press it, ride the lift back down, and run into the timed lift that just lowered in the lower prong of the "E". Press the switch there to open the gate to the exit switch (J). The teleport near the exit switch will take you back to the main area (on a ledge with an otherwise unreachable soul sphere, if you need it).

Official

 * 1) From the non-official secret (see below), turn back around and ascend the stairs. When you reach the top, a lift will lower back at the bottom of the stairs, along the south wall. Ride this lift up to a chaingun (L). To the left of the chaingun is a wall with pipes on it. Open this wall and follow the tunnel to the end, where you'll land on an otherwise unreachable platform with a blur sphere on it (M).
 * 2) After retrieving the blue keycard, return to the main area (the "O"). Along the eastern wall in the northern half of the nukage lake, a small opening will have opened. Go through and take the teleporter at the end to reach the Imp's platform (N).
 * 3) After passing through the red door, you'll go through a set of automatically-opening metal bars. The wall alongside the northernmost bar can be opened when the bars are opened. Take the passage out to the Hell Knight's cage, containing an invulnerability sphere (O).

Non-official

 * 1) Despite not being counted officially, it is notable for serving as a base for the first official secret mentioned above and is arguably better hidden than other secrets on the map. From the start, follow the path along to the right and take the next right through the doorway into a new area. You should be facing a set of stairs. Turn around, and look for the pool of blood on the ground to the left of the doorway you entered from (K). The wall behind the blood can be walked straight through in order to get the soul sphere behind it.
 * 2) At the very end of the map, just before the exit switch, there's a teleporter to your right. Take it to grab the previously-inaccessible soul sphere sitting atop the highest ledge seen at the start of the map.

Bugs

 * 1) In versions of Doom II prior to 1.9, the arachnotron that appears on Ultra-Violence near the left-side stairwell heading towards the blue-key room is partially placed (i.e it is stuck) inside a tree, and hence does not move or attack.
 * 2) Near the switch that activates the walkway leading to the red key platform, two spectres are immobile trapping another that is against the switch wall, which can be freed if the two stuck spectres are killed.
 * 3) There is a multiplayer-only energy cell pack (thing number 236) located Southeast outside the map border, rendering the item unreachable via regular means.
 * 4) Sector 32 (the platform outside the red-keyed door) is tagged "10" and has a teleport target (Thing type 14), but there is no teleporter that leads to this target. (look at a map editor if you don't understand.)

Routes and tricks
Because of a peculiarity of the Doom engine that allows the player to press a switch no matter how far above or below it they are, it is possible to skip a large amount of this map; the player can press the wooden skill switch mentioned in the final paragraph of the walkthrough from the nukage outside the red door, by hugging the ledge it sits on. Then the player can jump onto the cement walkway leading to the exit area from the main "O". It's also possible to jump from the imp's platform to take the red keycard, so it can be accessed without picking up the the blue key.

Records
The Compet-N records for the map are: