Arachnotron

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Revision as of 12:20, 13 August 2009 by Desulated (talk | contribs) (Doom 64)


In the upper courtyard of MAP11: Circle of Death, in Doom II, an arachnotron turns toward the player with intent to kill. The translucent effect on its plasma burst is a feature in some source ports.

The arachnotron is a spider-like monster introduced in Doom II. It is quite similar to the spiderdemon but smaller and with large eyes that change color depending on the monster's current state (moving, hurt, or attacking). It is supported by a metal chassis and his body consists primarily of a large brain, along with two small arms. Instead of a chaingun it wields a powerful plasma gun that fires bursts of yellow and green energy.

According to the manual: Maybe cybernetics wasn't such a great idea after all. Look what the demons have done with it. It seems unfair somehow you're not the only guy in Hell with a plasma gun.

Combat characteristics

Once the arachnotron engages an enemy it will continue to fire until the enemy moves out of its field of view or until the monster flinches in pain or is destroyed. Similar behavior can be observed with the spiderdemon and the heavy weapon dude.

Tactical analysis

Although they may seem slow, arachnotrons are actually faster than quite a few of the other monsters and can catch up with the player at an alarming rate. They have a medium pain chance, so rapid fire weapons will work well, although using the chainsaw on them is very risky. Their attacks are easier to avoid than the hitscan attacks of the other monsters that use rapid fire weapons, but the plasma bursts move faster than most other projectiles and can quickly hurt the player severely, if not avoided. If a player constantly attacks, moves in broad side-to-side movements, and tries to get out of the arachnotron's line of fire periodically, then the player will sustain minimal damage. Additionally, the projectiles fired by arachnotrons can obscure the player's vision.

Notes

  • As with the spiderdemon, the term arachnotron (roughly translatable as "spider instrument") is not absolutely literal, as they only have six limbs; two arms and four mechanical legs. Arachnids (spiders and such), on the other hand, have eight limbs. Curiously, while the Doom 64 version increases their leg count to six, they lack the arms.
  • In the Doom source code the internal name for the arachnotron is MT_BABY, and the root of its sprite name in the IWAD is BSPI, so the monster was arguably called baby spider during the development of Doom II.

Data

Attributes
ID # 68 (decimal), 44 (hex)
Hit points 500
Speed 12 map units per frame
(140.0 map units per second)
Width 128
Height 64
Reaction time 8
Pain chance 128 (50%)
Mass 600
Bits 4194310
Bits list

1: Obstacle

2: Shootable

22: Affects Kill %

Sprites & sounds
Sprite name BSPI
Alert sound DSBSPSIT
Chase sound DSBSPWLK
Action sound DSBSPACT
Pain sound DSDMPAIN
Death sound DSBSPDTH
Ranged attack
Type Projectile
Speed 25 map units per tic
(875 map units per second)
Damage 5-40
Shots per minute 263
Width 13
Height 8
Sprite name APLS (in flight)
APBX (impact)
Sound DSPLASMA (firing)
DSFIRXPL (impact)
Damage done by each plasma burst
Shots needed to kill Mean Standard
deviation
Min Max
Player (100%
health, no armor)
5.02 1.09 3 8
Player (100%
health, security armor)
7.16 1.23 5 10
Player (200%
health, combat armor)
17.99 1.97 13 22
Barrel 1.44 0.60 1 4
Trooper 1.44 0.60 1 4
Sergeant 1.80 0.75 1 4
Wolfenstein SS 2.75 0.78 2 5
Imp 3.16 0.86 2 6
Chaingunner 3.61 0.91 2 6
Lost Soul 5.02 1.09 3 8
Commander Keen 5.02 1.09 3 8
Demon 7.22 1.29 5 10
Spectre 7.22 1.29 5 10
Boss Brain2 11.68 1.70 8 16
Revenant 13.90 1.83 9 18
Cacodemon 18.27 2.04 13 22
Pain Elemental 18.27 2.04 13 22
Hell Knight 22.80 2.24 17 28
Arachnotron3
Mancubus 27.28 2.45 21 33
Arch-Vile 31.76 2.58 25 37
Baron of Hell 45.16 3.09 36 52
Spider Mastermind 134.41 2.61 128 140
Cyberdemon 179.12 2.55 173 184

  1. This table assumes that all calls to P_Random for damage, pain chance, impact animations, and backfire checks are consecutive. In real play, this is never the case: counterattacks and AI pathfinding must be handled, and of course the map may contain additional moving monsters and other randomized phenomena (such as flickering lights). Any resulting errors are probably toward the single-shot average, as they introduce noise into the correlation between the indices of "consecutive" calls.
  2. Assumes that direct hits are possible, which does not occur in any stock map.
  3. Hardcoded exception to infighting negates damage (excepting indirect damage caused by exploding barrels).

Appearance statistics

In classic Doom, the arachnotron is first encountered on these maps:

Game ITYTD and HNTR HMP UV and NM
Doom II MAP07: Dead Simple MAP07: Dead Simple MAP07: Dead Simple
TNT: Evilution MAP06: Open Season MAP08: Metal MAP04: Wormhole
Plutonia MAP03: Aztec MAP03: Aztec MAP03: Aztec

The IWADs contain the following numbers of arachnotrons:

Game ITYTD and HNTR HMP UV and NM
Doom II 15 41 64
TNT: Evilution 29 52 57
Plutonia 68 87 94

Other games

Doom 64

The Doom 64 arachnotron has 2 plasma guns. In addition its appearance is different: it is a bit higher, has 6 legs instead of four, it has red eyes insted of blue and the brains are smaller and more pink in tone. In combat, it fires the plasma shots in a semi-automatic fashion instead of entire streams.

Doom RPG

The arachnotron appears in as a class of monster. There are three variations, identified by color:

  • Arachnotron (normal colors)
  • Plasmodium (light green brain, bronz-colored robotic chassis)
  • Astaroth (light purple brain, gold-colored robotic chassis)

Arachnotrons attack three times consecutively, and are most weak against bullets and rockets.

See also