Alien Overview (Apocalypse)
This section gives a brief description of the various aliens in X-COM Apocalypse and groups them by threat levels towards human agents, with the exception of the Overspawn as it is a Cityscape-only enemy.
X-com: Apocalypse also introduced human enemies. While strictly speaking they aren't Aliens, they have been included in the list below for convenience's sake. Note that Organizations only employ standard humans; they never use Hybrids or Androids (this applies even to S.E.L.F. and the Mutant Alliance).
As different players will have varying comfort levels fighting against the different aliens based on their own experience levels, these groupings are not final and should be treated as estimates.
The multiworm egg is the first phase of the multiworm life cycle. It is armed with a weak short ranged spit attack but is otherwise harmless if left alone. They do not require any direct intervention and are recovered automatically at the end of the mission.
The chrysalis is the final stage of the multiworm life cycle, and serves as a universal egg of sorts that turns into any one of the aliens you will face. It is completely defenceless. Serving as ideal targets for shooting practice, they pose no threat and are automatically recovered the end of a mission.
Spitters are pink humanoids without a head. They spit acid at enemy targets from the funnel at the end of their neck.
Spitters are relatively easy enemies to fight, but their spit attack can be very dangerous if underestimated. They generally do their worst when fighting in groups or when they are lucky enough to score several critical hits in a short amount of time.
Brainsuckers are small basketball-like aliens with limbs. They function purely to take over the bodies of X-COM agents. They are small and fast and can leap great heights. They are transported in an inert state in small pods and can be launched from Brainsucker Launchers.
They have a very short lifespan that only lasts long enough for a single attack after they have hatched from their pods.
With their speed and ability to jump great heights, they pose a fairly dangerous threat to agents that are not vigilant.
Brainsuckers do not actively target X-COM Android agents. This effectively makes them immune unless the Brainsucker manages to land on an android by accident.
Primorphs are a psionic being that resemble a collection of large green tentacles as large as a Megaspawn. They hover slowly through the air. They only attack with psionics.
By itself a psimorph is a low threat and makes for a very easy target due to its large size. Its psionic attacks however can disrupt agents weak in psionics and even turn them against their companions. Like X-COM agents, they do suffer from the same limitations of having a psi-energy bar. They can easily be overwhelmed by many agents.
Against androids and skilled hybrids, the psimorph pose a non-existent threat.
The masterminds behind the alien threat. They are a minute species of psionic alien that, when grouped together, resemble a puddle of slime. Their only means of attack is through powerful psionic attacks.
Though more powerful than the Psimoprh, their physiques are weak. They make up for this with larger numbers (of puddles).
They share all the limitations of the Psimorph and are no threats to androids.
The hyperworm is the small offspring of a deceased Multiworm. When the Multiworm dies, four Hyperworms spring from its body to deal one last blow to the multiworm's attackers.
The individual Hyperworms are relatively weak and have a short ranged bite attack that do minor to moderate damage. Their strength comes from their speed and numbers.
Setting fire to the Multiworm just before it dies or use of high explosives are easy methods for quickly handling hyperworm swarms.
There are four types of human enemies, though they all have similar stats and equipment. Like your own agents, their stats vary from individual to individual. Their equipment will improve over time, and they will eventually acquire weapons of Alien origin. Finally, note that they have some weapons available before X-com can buy it (e.g Plasma Guns) - this means that raiding hostile organizations is a possible source of such weapons before they appear on the market.
Generally speaking, human enemies are not as dangerous as the weapon-wielding Aliens. However, enemies wielding Rocket Launchers should be treated as High threat.
Members of the Cult of Sirius will be a constant nuisance throughout the game. In combat they'll usually send one group to pin you down while the others try to outflank you. They use explosives liberally and without much regard for personal safety. Luckily, they aren't as well-armed as the gangs.
Megapol officers are well-armed, but vulnerable to Psionic attack. They will only be fought if you anger Megapol. You want to avoid this - Megapol is your only real ally aside from the Government.
All other organizations employ Security guards. While not as aggressive as the others, they can still pack heavy weaponry and should not be taken lightly. Wealthier organizations, such as Marsec or Solmine, have both more guards and better weapons.
The Multiworm is the mature stage of the multiworm life cycle. It is a very tough large worm that is able to launch a powerful and rapid spit attack against nearby agents. The large amount of health that the Multiworm has allows it withstand a fair beating before it goes down. On its death it releases four Hyperworms that attempt to swarm towards the nearest attacker. This makes melee or short ranged combat against them a risky practice.
Multiworms are a very highly valued Biochemistry project.
The Popper is a bomb with legs. The Popper is very agile and can move at an amazing pace across the battlefield. Its body heat causes it to leave wafts of smoke wherever it runs. Though they have no ranged attacks, they will explode when they are next to an X-COM agent.
The only way to defend against these enemies is to constantly be on alert, or to be flying well out of its reach. In Real Time combat, actively scanning the area with a motion scanner for rapid moving blips can save many lives.
Poppers will also explode when killed by solid round projectiles, explosions or from blood loss. They will not explode from energy weapons or gas.
The Anthropod is the basic foot soldier of the alien invasion. They look like blue veiny blobs with elephantine limbs. Despite their almost comical appearance, their ability to make use of a variety of armaments and tools makes them very deadly foes.
The Anthropod is one of the two aliens available to the aliens that are capable of wielding tools.
The skeletoid is a boney yellow patchwork man. They are identical to the Anthropod in threat and function with the addition of a hovering ability. This means that they are able to attack from the air and reach places that Anthropods can not go to.
The ultimate form and mother of the Multiworms. It is the largest creature that you will face. It is immobile but makes up for this by having an incredibly powerful and fast firing ranged attack that can easily best even the most heavily protected agent.
Although the Queenspawn can only attack directly in front of it and it is immobile, the major portion of its perceived difficulty stems from its environment. It is placed on a dais that is surrounded by a solid organic alien building wall on one side, and laser curtains are provided on each of its sides to protect its vulnerable sides. This means that it can only be approached from the front. Four re-enforcement teleport pads beyond the dias provide additional troops for it.
Capture of this alien allows for progression of the Alien Gas toxin weapon research.
The queen can only be found in the Spawning Chamber.
The Megaspawn is an alien built like a tank that is armed with a built-in Disruptor beam that is as powerful as a Devastator cannon and a seemingly endless supply of dimension missiles. One Megaspawn can easily lay waste to an unprepared team of agents.
They are not without their faults, and their size is one of them. Their larger size makes them easier targets to hit. While it is not always the case, they appear to have some reluctance to fight agents that are right up next to them and will turn and run.