Arachnotron

A group of Arachnotrons turn toward the player with intent to kill in MAP07: Dead Simple, in Doom II.

"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."

― Description in the Doom II manual

The Arachnotron is a spider-like cybrid monster introduced in Doom II. It is similar in appearance 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 a body that 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.

In Doom II, they make their first appearance in Dead Simple, where the player must fight them when they reinforce the fallen Mancubi.

Combat characteristics

An Arachnotron lets out a crescendoing mechanical cry (akin to machinery powering up) when spotting a player; like the Spiderdemon it has audible footsteps, in their case sounding like buzzing machinery punctuated with occasional electronic crackling. Once the Arachnotron engages an enemy it will continue to fire until the enemy is killed or 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, nazi soldier, and heavy weapon dude. When this monster dies, its head explodes into a morass of gore as its mechanical body collapses while unleashing a dying tone that resembles failing machinery.

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 such as the chaingun will work well, although using the chainsaw on them is very risky (unless the chainsaw-wielding player can rapidly reach the monster to start sawing it before it starts firing). Their attacks are easier to avoid than the rapid-fire hitscan attacks of heavy weapon dudes and Spiderdemons, but their plasma bursts are among the fastest projectiles, and their high rate of fire can quickly drain the player's health. Additionally, the plasma bursts can obscure the player's vision upon a successful hit. 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.

Because of their sustained, extremely fast rate of fire, they are often more than capable of defeating almost any monster if provoked via monster infighting, especially when multiple Arachnotrons attack; however, stronger enemies such as a baron of hell will usually prevail in smaller battles because of their higher health.

Notes

• As with the Spider Mastermind, the term Arachnotron (roughly translatable as "spider instrument") is not absolutely literal, as arachnids (spiders and such) have always eight limbs. In Doom 2, however, these monsters have only six limbs: two organic arms and four mechanical legs; curiously, while the Doom 64 version increases their mechanic leg count to six, they lack the organic 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 (or nicknamed) baby spider during the development of Doom II.
  • In the Ultimate Simpsons Doom PWAD, the animation frames for the Arachnotron are replaced with images of Maggie Simpson, presumably as a deliberate pun on this MT_BABY designation.
• In a ZDoom-based source port, if the player is killed by an Arachnotron (monster is credited with delivering the blow that reduces player's health to 0%), an obituary message is displayed at the top of the screen: "[player name] let an Arachnotron get him(her)".
• The projectile sprite APLS is actually a re-colored version of the Imp's projectile sprite in beta versions of Doom.
• The Arachnotron was supposed to have a Chaingun instead of a Plasma gun in the early beta of Doom II.
• In Brutal Doom, Arachnotrons are larger, near the size of Hell Knights or a Baron of Hell, move faster and fire the same blue plasma bolts from the player's plasma gun.

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%) Pain time 6 tics 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

Doom 64's Arachnotron in action.

In Doom 64 their physicality is considerably altered; the mechanical body is much bigger, with the brain head ducked down inside the machine itself instead of sitting atop it, also not having any organic arms like the classic version, and the mechanical legs (now six instead of only four) being longer and bent at upwards-pointing acute angles. Instead of a single plasma gun, the Doom 64 Arachnotrons possess two guns that fire out two blue plasma bolt shots simultaneously, but done so in spurts of five instead of a constant rate of fire, though it will continue firing as long as it can see the player. They first appear in MAP14: Eye of the Storm unless the player goes through MAP30: The Lair and MAP32: Hectic, which contain Arachnotrons but chronologically come first.

See also

• Monsters open locked doors

Template:Sony PlayStation monsters