Capturing Live Aliens (Apocalypse)
Unlike in previous and subsequent X-Com games, the primary goal of X-COM: Apocalypse - destroying the alien city - can be accomplished without capturing any live or dead aliens. However, capturing aliens is essential to the secondary goal of discovering what the aliens are planning, and also unlocks the immensely-powerful Toxigun, so it can be thought of as a sidequest.
There are several distinct stages of this research path, which are worth keeping in mind when deciding which aliens to bother capturing. Each stage's information and toxin technology requires that of the previous stage.
- The Alien Genetic Structure and Biological Warfare, the latter of which provides the Toxigun itself and Toxin Type A, merely require the autopsy of any one immature alien (Multiworm Egg, Multiworm or Hyperworm).
- The Alien Life Cycle and Toxin Type B require the live examination and autopsy of the Multiworm, Hyperworm and Chrysalis - as you'll see below, the Multiworm is the only tricky one here.
- The Real Alien Threat and Toxin Type C require the live examination and autopsy of the Multiworm Egg, Brainsucker, Anthropod, Spitter, Popper, Skeletoid, Micronoid Aggregate, Megaspawn and Psimorph - i.e., every alien except the Queenspawn and Overspawn.
- Alien Gas requires the live examination and autopsy of the Queenspawn.
(Additionally, you will need to research the Bio-Transport Module and Advanced Biochemistry Lab; both should be considered high-priority if you wish to pursue this path, although in the former case there's nothing else to research yet anyway.)
The important thing to note here is the enormous gulf between Toxin B and C; capturing a Multiworm is a high priority, as it is the only significant capture requirement for Toxin B, but unless you're willing to bother capturing all the aliens needed for Toxin C there's little reason to bother capturing any of them (or to capture the Queenspawn). Toxin B is already exceptionally good, so decide early on whether you want to get Toxin C and play accordingly.
Note that you don't need to separately capture an alien alive and dead like in UFO or TFTD; examining a live alien will give you the corresponding corpse.
Methods of capture
There are three methods of stunning aliens in order to capture them alive: the Megapol Stun Grapple, the Megapol Stun Grenade and the psionic "stun" attack with a Mind Bender. Each has advantages and disadvantages.
- The Stun Grapple requires little micromanagement, is cheap and has infinite ammunition, but is short-ranged and cannot penetrate Personal Disruptor Shields.
- The Stun Grenade ignores shields and has medium range, but the cloud of stun gas dissipates quickly and also affects X-COM personnel; the grenades are also consumable and must be manually transferred to hand as needed. It also has no effect on Micronoid Aggregates.
- Psionic stunning can be done anywhere within line of sight, ignores shields, and only uses (regenerating) Psi-energy, but you'll need to train hybrids to do it and it only has a high success rate on Anthropods and Skeletoids.
General capture procedure
The ideal way to capture aliens goes roughly like this:
1) Set up a situation where you can afford to concentrate on the capture. This means eliminating or drawing off other aliens, as well as bringing the proper equipment and/or soldiers to make the target itself less dangerous (you don't generally want to be risking soldiers for a capture).
2) Perform the capture. For most aliens, this simply means sending a few soldiers in with Stun Grapples or Stun Grenades while having the rest of your squad hold their fire. However, the maximum stun level is 255, and some aliens (Multiworms, Megaspawn, Psimorphs and the Queenspawn) have more health than this; you'll need to carefully damage them with weapons while keeping a fairly-constant stun level on them.
3) Pin the alien to the ground by having a soldier stand on top of it. This prevents the alien from "waking up" as its stun level decreases over time. It's generally best to put the soldier used for this in a squad by himself, so that you don't accidentally move him.
4) Complete the mission. Try to do this quickly, and without explosives going off near the unconscious alien (as unconscious aliens may be bleeding from critical wounds, and will still take damage from explosives).
Specific alien notes
The Multiworm Egg, Hyperworm and Chrysalis do not need to be stunned in order to research them. The Multiworm Egg and Chrysalis are recovered alive automatically if left alone, and researching a live Multiworm puts four Hyperworms into your Alien Containment.
Brainsuckers, Spitters and early-game Anthropods pose very little threat at range, so capturing these is a simple matter of walking up to them with a Stun Grapple (or, in the case of Brainsuckers, having a Stun Grapple in hand when they charge you).
You can also put a live Brainsucker into your Alien Containment by recovering and researching an unhatched Brainsucker Pod, although this takes extra research time.
The problem with Multiworms is simply their high health and their high rate of fire. The safest way to capture these is to use Stun Grenades from long range (exploiting the short range of Multiworms' spit and their inability to escape the gas cloud) while chipping away with weak weapons like the Lawpistol, M4000 and Laser Sniper Gun (to reduce their health below the stun limit without inflicting critical wounds).
Alternatively, charging in to point-blank range with a full squad of soldiers in Megapol Armor dual-wielding the above weapons with Stun Grapples will almost always bring down a worm before it can kill any of them (though they'll usually be wounded).
Poppers are easy enough to stun, assuming you see them coming (in real-time mode) or get the drop on them (in turn-based mode). What's worth noting is that Poppers take critical wounds very easily and will explode if they bleed to death. As such, you should ensure a Popper is undamaged if you plan to have an Agent stand on it.
While Skeletoids are very similar to Anthropods in most respects, they only show up in Week 3. Depending on X-COM's performance, this means that they may already be equipped with Devastator Cannons. A Skeletoid, or even Anthropod, with a Devastator Cannon is a serious threat at long range, and attempting a live capture will frequently result in soldier deaths. The humanoid aliens will also eventually gain access to Personal Disruptor Shields, which negate Stun Grapples.
Nabbing a well-armed Skeletoid safely is best done with psi from behind cover (line of sight is only required for the initial lock), or opportunistically (with Stun Grapples if encountered at close range, or with Stun Grenades if many Skeletoids are encountered in an enclosed space). If you find a lone Skeletoid with a Brainsucker Launcher or Disruptor Gun, of course, such caution is unnecessary.
The Psimorph and Micronoid Aggregate are very similar in that their only method of attack is psionic powers. Psionic powers are very effective against your human soldiers, but ineffective against androids or well-trained hybrids. As such, the trick here is to get them on their own (without supporting aliens) and send in a squad of only hybrids or androids - this renders them toothless and assures an easy capture (Psimorphs will need to be damaged, but with this tactic you'll have plenty of time to do it carefully).
Note that Stun Grenades are not very useful against either of these; Micronoids are immune, while Psimorphs can fly and have a great deal of health.
Megaspawn are a notoriously-difficult capture due to their heavy armament - in particular, their infinite supply of long-range homing missiles. The ideal way to capture a Megaspawn is to wait until you have X-COM Disruptor Armor, which largely obviates their missiles as a threat, and/or Personal Cloaking Fields, which prevent them from targetting your soldiers at long range (unless another alien is spotting for them).
If you aren't willing to wait that long, the best bet is to use several soldiers, each with a Stun Grapple and two shields and one additionally holding a Devastator Cannon, and try to take a Megaspawn by surprise in the cramped rooms of a UFO. Expect lost shields and possibly soldiers.
The Queenspawn capture is a bit complicated due to her tentacle whip, but quite easy with Cloaking Fields, 20 or so Stun Grenades, and patience. Given the very fixed nature of the mission (she's always in exactly the same place and can't move), this section will be quite detailed.
1) Kill all the mobile aliens on the map, and blow up all the reinforcement pads. This deprives the Queenspawn of spotters, making her harmless to cloaked soldiers at medium to long range.
2) Throw two Vortex Mines into the raised dais holding the Queenspawn, one on each side of her. These will inflict some damage and, more importantly, destroy the Multiworm Eggs around her (allowing the mission to end as soon as the Queenspawn is stunned).
3) Start throwing Stun Grenades at the Queenspawn. Wait for the gas cloud to nearly dissipate before throwing the next grenade, to get the maximum effect from each grenade.
4) After five grenades or so, if she is not stunned, have a soldier start shooting her with a Devastator Cannon on aimed shot (to inflict damage slowly; a Toxigun will often be too fast and kill her in the couple of seconds before the mission ends). Keep throwing Stun Grenades until she drops.