E1M8: Phobos Anomaly (Doom)

E1M8: Phobos Anomaly is the eighth and final map of Knee-Deep in the Dead in Doom, featuring a boss battle with two Barons of Hell. It was designed by Sandy Petersen and Tom Hall and uses the music track "Sign Of Evil".

Walkthrough

 * Letters in italics refer to marked spots on the map. Sector numbers in boldface are secrets which count toward the end-of-level tally (if your source port displays one).

Essentials
From the start point (A), walk forward and click the switch to lower the brick wall. Jump down into the oval room, then take the staircase to your left (north). Proceed through the gray door and along the central hallway to a square button (B). This button lowers a one-way elevator which leads to a large star-shaped room, at the center of which are two rectangular, tomb-like structures (C). Each of these contains a Baron of Hell, and opens as you leave the red alcove. If you play on Ultra-Violence or Nightmare!, there are also ten Spectres here, two in each corner of the star; these are difficult to see because the room is fairly dark and has a speckled floor texture.

To proceed further, you must kill the two Barons. This is easiest if you have a rocket launcher from a previous level, although you should watch for Spectres cutting in front of you and subjecting you to blast damage. Otherwise, note that the chaingun has a higher rate of damage than the shotgun, which gives the monsters less time to corner you. If you run low on ammunition, the corners of the star contain four bullet boxes and a shell box, as well as a shotgun, two medikits, a stimpack, and a blur artifact.

When both Barons have died, the walls of the star will slowly open, revealing a huge rectangular courtyard outside. At the north end of this is a marble-textured teleporter pad on a gray platform (D), which is invisible on the automap. Pull the switch at the base (E) to raise its stairs, and ascend to the teleporter. This deposits you in a pitch-dark, inescapable room with a pack of monsters around you and slime under your feet (F). As soon as your health drops to 10% or lower, the level ends.


 * For more detailed tactical advice, see Baron of Hell.

Other points of interest
The oval room contains a number of barrels, which surround four Demons (I'm too young to die and Hey, not too rough) or eight Demons (Hurt me plenty), or twelve Demons (UV and NM). It is possible to clear the entire room with barrel frags, though usually at least one or two Demons will survive. For a single chain reaction which destroys every barrel, aim at the leftmost or rightmost barrel you can see, not at the barrel closest to the start point.

At the eastern end of the oval room, you can ride a slow-moving lift up to a ledge (G) containing a computer map, a bullet box, and ten stimpacks. If you exit the lift while it is fully lowered, however, it will rise without you, blocking the ledge permanently.

Just past the gray door, there are dark rooms on both sides of the hallway. In the right (east) room is a chaingun with several bullet boxes; to the left (west) is a shotgun with several shell boxes.

[Added in Ultimate Doom] Inside the eastern "tomb", there is a secret compartment on the east wall (H). Opening it reveals a switch, which re-activates the elevator at the south end of the room, allowing the player to return to earlier sections of the level. This compartment is not needed for 100% secrets.

Secrets

 * 1) Near the bottom of the staircase leading to the gray door, there is a secret compartment on the east wall, indicated by a greenish texture (I).  Open this to reveal a soul sphere. (sector 59)

Bugs
The blockmap bug can be triggered by attacks directed


 * north-south in the star room near the star's axis of symmetry;
 * eastward out of the western point of the star;
 * along the central corridor.

After the walls of the star have been lowered, examination of its inner corners may reveal a handful of slime trails (see screen shots below).

Routes and tricks

 * The computer map and shotgun are not needed, so the areas containing these may be bypassed.
 * If the player is positioned at one of the five points of the star-shaped boss battlefield, demons and spectres cannot get close enough to cause damage.
 * It is possible, but difficult, to jump directly from the boss battlefield to the top of the teleporter structure, thus avoiding a delay waiting for the stairs to rise. The player must straferun-jump just as the top of the lowering wall meets the level of the battlefield, in effect extending it out further. Some of the speedrun demos below demonstrate this maneuver.

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


 * 1) Compet-N does not maintain a UV -respawn competition for this level; the reasons for this are unclear. [1 ]

Technical information
Having the walls lower when the last boss has been killed is a special effect built into the Doom engine. The walls to be lowered are given the special sector tag of 666. Because the level uses this effect, and there is no other way around the walls, it is impossible to complete the level in "no monster" mode (except by cheating).

The damaging floor in the last room is a special sector type (11), more specialized than the usual damaging floors. It turns off "god mode" if it is on, and ends the level when health is depleted. This sector type is available but rarely used in PWADs.

A par time of 30 seconds is defined in the source code (g_game.c), but is never actually displayed, even in source ports which generate intermission screens for the final level of each episode.

Inspiration and development
An early version of this level appeared as E1M12 of Doom 0.5.