Let's say there are two different groups of aliens in close proximity, and one of the aliens of the first group is alerted ("awakened") to my presence. Will the other group also become alerted?

In other words, if I know / suspect that there are two groups nearby somewhere, is it viable to try to advance really slowly to try to just alert one without the other?

1 Answer 1


The aliens "communicate" only with other awakened groups. However, their behavior of the "sleeping" squads will change according to the mission:

  • If it's a normal abduction or downed/landed craft they will just sit quietly in their spot until you "activate" them. Only the activated groups will take part in the action. One time even happened to me that I had an inactive group at the very edge of my line of sight (I saw only one and a half of the three aliens in the group) and an alien retreated back to where they stood, and they still were inactive. There is an exception to this with mechanical enemies (the Cyberdisk and the Sectopod), Floaters and Mutons, which roam the battlefield and don't wait in one place, so they can activate themselves by entering your LOS.

  • On a terror mission, the aliens are all roaming through the battlefield trying to kill civilians, so they can enter into your line of sight and then get activated, like the roaming enemies during abduction/UFO missions. However, both enemies on a terror mission and roaming units will not move to engage you, but rather move on the battlefield without clear purpose until they are activated. So they will not pursue you until they are activated, and if they are the ones that enter your LOS, they will not have time to engage you, which will give you 1 turn to deal with them, before they attack you.

  • On bomb disposal and extraction missions there are 2 types of enemies: the enemies that are already in place, who will act as normal enemies and not get activated until you activate them, and the thin men reinforcement (the thin men that drop from the sky toward the end of those missions). The reinforcement aliens are activated from the minute that they enter the battlefield, so even if one of them is far away from you, you can be sure that it'll move in order to engage and attack you.

  • I've seen behavior where aliens will intentionally retreat to an area where there are additional unactivated aliens though, trying to lure you into a trap.
    – l I
    Commented Nov 13, 2012 at 12:03
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    @spartacus, I'm not sure that it's on purpose, I think that it's random, or maybe their retreat algorithm chooses this place because of better cover or something. In any case, if you'll stay put and not move, the new aliens at the place where they retreated will not be active.
    – SIMEL
    Commented Nov 13, 2012 at 12:13
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    Pretty sure Aliens can patrol on abduction missions. It may be less likely on lower difficulties, but they definitely do it. And I know they patrol on downed/landed craft Commented Nov 13, 2012 at 14:15
  • Yep, floaters and mutons do patrol.
    – Orc JMR
    Commented Nov 13, 2012 at 14:33
  • Added the data about muton/floater patrols.
    – SIMEL
    Commented Nov 13, 2012 at 17:37

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