Overviews of Aliens

As a first step a commander should be aware of the basic details of the threat facing the Earth, to this end an Overview of Aliens can act as a first step in preparing the novice for their first clashes on the battlefield. Once the commander is conversant with this information further details can be found by looking at aliens' specific pages or Alien Stats.

Low Threat

Low Threat: Sectoid

The Sectoids are possibly the first alien you'll see. They resemble the "Greys" spoken of by New Age types and the X-Files television show: short humanoids with pale skin, elfin features and large, almond-shaped eyes.

Sectoids are very weak in combat, with generally poor accuracy and reaction time. They have mediocre mobility, no armor worth mentioning, and will easily fall under standard rifle fire, grenades, or even a glancing shot from heavier weapons. Without their more devious Sectoid Leaders, they can be overcome with minimal risk.

However, on any mission that doesn't involve a small-sized UFO (Small Scout, Medium Scout, or Large Scout), the Sectoids will have a Sectoid Leader in their ranks. This Leader is capable of Psionic attacks that can panic your troops or even bring them under alien control, to be used against you. In the early game when Sectoid sightings are common, this can be devastating because X-Com has not yet researched Psionics, and so is wide open to psionic warfare.

Furthermore, on any Mission involving terror units, the Sectoids will be accompanied by the formidable Cyberdisc, which adds another degree of complexity to the situation.

See also: Sectoid | Medium Threat: Cyberdisc - Terror Unit

Low Threat: Floater

The Floaters are the other variety of aliens you'll see early in the game, possibly before Sectoids. They are purple humanoid shapes clad in capes, floating perpetually above the ground. They are more formidable in combat than the Sectoid. They have better firing accuracy and reactions, along with a modicum of armor. They have somewhat better mobility than the Sectoid, and they are capable of floating in mid-air. They use this ability only rarely (almost never on lower difficulty settings), but it does mean that, at game start, you will see them more frequently on rooftops and other elevated positions. They rarely make good use of cover while floating above ground level. Floaters may be more likely than Sectoids to throw grenades, but hard data here is lacking.

While Floaters, by themselves, are more fearsome than Sectoids, they lack the Sectoids' two advantages: Floaters have no Psionic capability, and their terror unit, the Reaper, is mediocre at best. Floaters arguably make for the easiest large UFO missions, terror missions and alien base attacks due to these weaknesses.

See also: Floater | Low Threat: Reaper - Terror Unit

Low Threat: Reaper - Terror Unit

The Reaper is the dedicated Terror Unit of the Floater, and will only be seen accompanying them. It is a large, furry mammalian biped of size comparable to an X-Com HWP. It is armed only with its bite, which obviously can be used only when the alien is directly adjacent to its foe. It is arguably the least threatening alien in the game. Since they are so large, reapers are generally easy to spot and easy to hit. While they can absorb a considerable amount of damage, they are resistant only to armor-piercing fire and make a large target. They are particularly vulnerable to incendiary fire, but almost any heavy weapon fire will dispatch them without much trouble. Their only real assets are their high mobility and ability to absorb damage.

See also: Reaper | Low Threat: Floater

Low Threat: Silacoid - Terror Unit

The Silacoid is one of the two varieties of Terror Units deployed with Mutons, and will only be seen accompanying them. It resembles a large pink rock that slowly rumbles along the ground, often leaving a trail of burnt terrain in its path. Their only combat ability is to make a moderately damaging melee attack, presumably involving the burning heat of its body. Its mobility is lacklustre, and the burnt trail it leaves makes it easy to track. They are somewhat well armored and can absorb a moderate amount of fire. Considering that they are usually only encountered in the mid- to late-game, the sight of this underwhelming combat unit comes as a pleasant surprise to Commanders accustomed to more fearsome prey.

See also: Silacoid | High Threat: Muton

Medium Threat

Medium Threat: Celatid - Terror Unit

The Celatid is one of the two Terror Unit types deployed with Mutons, and will only be seen accompanying them. It resembles a large, pink kidney bean that hovers along slowly at ground level. It attacks by spitting venom at its target, and can do so with great accuracy. This venom is extremely dangerous to unarmored units, while somewhat less threatening to armored troops and HWPs. It can only project its venom over a short range (perhaps 7 squares), and has relatively low mobility. It has negligible armor and can be destroyed with standard weapon fire, or glancing fire from heavier weapons.

The science division says that a celatid is capable of tracking units outside of its line of sight, but there is no field evidence to confirm this. In any case, it is at home in close quarters, particularly indoors where it can pop out from around corners, and its small size can make it a somewhat difficult target to hit. However, its low mobility, short attack range and vulnerability to fire means that, with proper care taken, it is only a moderate threat on the battlefield.

See also: Celatid | High Threat: Muton

Medium Threat: Cyberdisc - Terror Unit

The Cyberdisc is the dedicated Terror Unit of the Sectoid, and will only be seen accompanying them. It is a mechanical floating disc, comparable in size to our HWP, though it has a lower profile. It has moderate mobility, and can float at any level above the ground. It attacks with a devastating plasma shot, capable of firing up to three snap shots in a round with good accuracy and reactions superior to our HWPs.

It is resistant to armor-piercing weapons, and holds up well against psionic manipulation. Its slim profile can make it a difficult target for an object of its size. Worse, when it is destroyed, it usually explodes with a ferocity comparable to Alien Grenade or worse. New commanders often have difficulty destroying it with Terran weapons; it is advised to direct as much firepower as is available against one. Alien weapon technology is far more suitable for destroying it.

Commanders should remember that any mission involving Cyberdiscs will also involve Sectoids with Psionic capability. However, not all missions with psionic Sectoids will involve Cyberdiscs.

See Also Cyberdisc | Low Threat: Sectoid

Medium Threat: Snakeman

Snakemen usually won't show up for at least two or three months into the game. As their name suggests, they are reptilian, resembling snakes with arms, slithering along on their lower bodies. They have noticeably better armor than floaters or sectoids, and are capable of absorbing significantly more fire than either. Their combat stats are at least comparable to Floaters, possibly slightly better. They seem a little more willing to use grenades than Sectoids or Floaters, too. Their key flaw, however, is low mobility. They are not able to move very quickly, slower even than Sectoids.

However, larger Snakeman missions involving Terror Units can be truly fearsome, with the inclusion of their devastating Chryssalid support units.

See Also Snakeman | High Threat: Chryssalid - Terror Unit

High Threat

High Threat: Chryssalid - Terror Unit

The Chryssalid is the dedicated Terror Unit of the Snakeman, and will only be seen accompanying them. One of the most feared enemies of X-Com, these creatures have shiny black exoskeletons, an insectile look, and a toothy grin. They resemble the art of H.R. Giger. They have incredible mobility, lightning-fast reflexes, and can absorb large amounts of fire. These abilities allow them to slug it out long enough to deliver their chief threat: their infectious bite, which can penetrate even the thickest armor and can destroy HWPs.

The ability of a single specimen to turn an entire troop of X-Com operatives into a new population of Chryssalids is the stuff of a Commander's nightmares. Killing chryssalids should be your top priority whenever they are present. Concentrate fire upon them. Don't be afraid to sacrifice any civilians or X-Com troops nearby-- if the chryssalid doesn't die, they'll probably be infected anyway. Ensure that all Chryssalids that drop are dead, not merely unconscious. Listen for a lack of a death-cry - do not hesitate in blowing up its body to finish the job.

Zombie

Any X-Com trooper or civilian bitten by a cryssalid will turn into a zombie-- a harmless, drooling humanoid that runs around and tries to launch weak physical attacks against your troops. The creature itself is harmless and easily killed.

[Darksun: Mostly harmless. The melee attack can kill a soldier in a t-shirt in one turn. Don't let them stand next to you for long. If you can't burn it and aren't ready to concentrate firepower on the emerging chryssalid, you should keep your distance. Your soldiers will happily zap them with reaction fire. This can be a worse disaster than just letting the zombie beat a single trooper to death.]

Unless zombies are burned to death with an incendiary attack, a chryssalid will hatch out of its corpse when is it killed. The new chryssalid is at full strength and has all the abilities of a normal chryssalid -- including the ability to turn more people into zombies and 100% of it's TU's. Yes, this means that a single Chryssalid can turn every human on the board into a Chryssalid.

See Also Chryssalid | Zombie | Medium Threat: Snakeman

High Threat: Ethereal

Ethereals are the ruling caste of the Alien hordes. They will not be seen until the late in the game, but when they do, expect them to be armed with the most powerful weapons in the alien arsenal. Their bodies are thin and emaciated, with pale, pinkish skin. However, they only appear in combat wearing billowing orange robes which make their narrow frames look more imposing.

They can endure large amounts of damage and have very good combat skills. They also have good mobility and are able to fly, which they do with little hesitation. Every Ethereal has psionic ability; expect psionic warfare to commence almost immediately in any combat against them. Always engage Ethereals with the greatest caution, and all knowledge of psionic combat you have at your disposal.

As if their combat skills, high mobility, resistance to fire and psionic ability were not enough, they also have one of the strongest terror units in the game-- the Sectopod.

See Also Ethereal | High Threat: Sectopod - Terror Unit

High Threat: Muton

Mutons are the shock troops of the Alien invasion, possibly the most skilled combatants you'll go up against. They usually won't show up until mid- to late-game, but when they do you can expect them all to be packing the most powerful weapons in the alien arsenal. They have purple skin, but everything but their faces are covered with thick, green, skin-tight armor.

They are heavily armored and capable of absorbing heavy fire, and are especially resistant to armor-piercing rounds. They have very good reactions and mobility, and average accuracy. They will lay down heavy fire and use grenades quite freely.

They are not without their weaknesses, however. They are known for a short attention span, and will forget the presence of enemies beyond their sight more quickly than other aliens would. They are vulnerable to psionic attacks, and have no psionic talents of their own.

They are the only species in the Alien invasion with two varieties of terror unit, the Celatid and the Silacoid. However, neither of these creatures can come close to matching the Muton's combat prowess.

See Also Muton | Low Threat: Silacoid - Terror Unit | Medium Threat: Celatid - Terror Unit

High Threat: Sectopod - Terror Unit

The Sectopod is the dedicated Terror Unit of the Ethereal, and will only be seen accompanying them. They are large, bipedal robots comparable in size to one of our HWPs. They are the most heavily armored units of the Alien horde, resistant to almost all forms of damage including even alien weaponry, requiring heavy fire to destroy one. Its only known weakness is to Terran laser weapons, and even against those it can sustain a good degree of damage.

They attack with dual head-mounted plasma weapons that are capable of automatic fire. They can fire with a high degree of accuracy and reactions far superior to our HWPs. They also have good mobility.

Some commanders keep special weaponry on hand exclusively to deal with them, including the Tank/Laser Cannon and even the otherwise shunned Heavy Laser. Blasters will do the job, but direct hits are usually required-- and occasionally may not be enough.

See Also Sectopod | High Threat: Ethereal

Notes

• The leaders of the alien horde are heavily dependent on psionic combat, and have even designed their mechanical units to respond to psionic stimuli.
• Only Sectoid Leaders, Sectoid Commanders and Ethereals (of any type) are capable of psionic warfare.

See Also

• Alien Life Forms
• Terror Units
• Alien Stats
• Overviews of Aliens (TFTD)