Difference between revisions of "Learning AI"

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Artificial Intelligence
 
Artificial Intelligence
 +
 
The Tactical Game uses a sophisticated Al system to control non-player forces. The system will adapt to your tactics by learning from its actions. This adaptation process occurs after each Tactical Game is played. The computer analyses an experience data file in order to update its decision matrices.
 
The Tactical Game uses a sophisticated Al system to control non-player forces. The system will adapt to your tactics by learning from its actions. This adaptation process occurs after each Tactical Game is played. The computer analyses an experience data file in order to update its decision matrices.
 
The Al does not cheat (ie it has no privileged information or abilities beyond that of a human player). The data files for the Al are not stored as part of a saved game, they are continually updated. You can exchange the files with other X-COM players in order to experience different tactics from the Al player. Ensure that you exchange all three of the relevant files that are located within the TACDATA subdirectory.
 
The Al does not cheat (ie it has no privileged information or abilities beyond that of a human player). The data files for the Al are not stored as part of a saved game, they are continually updated. You can exchange the files with other X-COM players in order to experience different tactics from the Al player. Ensure that you exchange all three of the relevant files that are located within the TACDATA subdirectory.
 +
 +
FilmBoy say that its working on UK CD release and not in US or some others, also its need phisical CD inserted and no use dosbox
 +
 +
below is scan of page from book X-COM Apocalypse: The Official Strategy Guide (Secrets of the Games Series) Paperback – August 26, 1997 by Dave Ellis
 +
[[Image:Learning_AI.jpg|800px]]
 +
 +
 +
==Unit Behavior==
 +
A list of actions, abilities, reactions and more, within X-Com Apocalypse. All actions mentioned here are present in the final version release unless noted with '''Debug'''.
 +
 +
===Agents on Normal or Safe behaviour settings on Vanilla and BETA will:===
 +
*Hide behind other agents that are kneeling and shoot over their heads
 +
*Agents placed at a corner to a corridor will move back and forth between hiding "in cover" and exposing themselves around the corner to shoot/view
 +
*Agents jump over 1-tile "gaps" in floors if it gets them to cover
 +
*Agents will jump down a maximum of 1 tile if it gets them away from fire to another floor or if injured to get them to a safer place
 +
*Agents will strafe back and forth whilst moving in and out of cover, even along a line of kneeling agents and shooting over their heads
 +
*Agents will run away from fire
 +
*Agents with a partially "stunned" value will run out of smoke to avoid being "gassed" further, this means that they can expose themselves to weapons fire but minimise the risk of falling unconscious
 +
*Agents with no "stunned" value will remain in smoke to utilise it as cover though often go prone or kneel if both stances are selected
 +
*Agents equipped with trackers (beta only) or scanners will "enhance" the behaviour of other agents in their squad (No effect on other squads). For example, agents in cover will respond to a blip by moving around corners to look down corridors or into rooms.
 +
*Agents raise weapons in readiness in response to alien cries
 +
*Agents raise weapons in readiness in response to nearby explosions, civilian screams and the sound of burning
 +
*Agents respond to alien cries as per the documentation i have given in the relevant thread
 +
*In Tactical Missions relating to Cityscape activity, spitters will wander around, when there are more than two **mobile** aliens on the map, trying to kill civilians (their main function it appears) and sniping at X-COM. If there are few aliens on the map, spitters will try to hide, often in obscure places of the map and in smoke until agents find them.
 +
*In UFO recovery, spitters will frequently hide in the upper levels of the UFO trying to avoid engaging X-COM and not really being utilised by the aliens. If they do travel to the lower decks or outside it is with Anthropods or Skeletoid allies. This behaviour seems bugged; spitters are sitting ducks in UFO missions and should be more active IMHO having the AI waste them by sitting in the upper levels makes no sense.
 +
*Brainsuckers can appear on maps at the start of a mission without having hatched from a pod
 +
*Brainsuckers will run around the map until they find an X-COM agent, though they often "pause" and become inactive, this is likely a bug.
 +
*Brainsuckers will attempt to run and leap on to the first agent they encounter to brainsuck them
 +
 +
*https://www.youtube.com/watch?v=YE0AXGppZtU
 +
**Brainsucker gets "stuck" and promptly shot after recovering from stun.
 +
**Agents strafing and hiding around corners
 +
**Brainsucker cry from the right of the screen (in darkness) allowing me to locate the last brainsucker and kill it winning the mission (cries can be used like this in vanilla, fortunately, my agent did not panic this time around as i sent him down a corridor alone).
 +
**Anthropods working alone and not in groups as they did in beta
 +
**Agents will react to alien sightings and fire whilst running, in this case saving me from a leaping brainsucker
 +
 +
* Beta2 https://www.youtube.com/watch?v=_DvtnGSUsUU
 +
**Beta Footage in which the aliens sabotage their own brainsuckers by destroying the escape route to the cityscape for a lone brainsucker. Also shows Anthropods sending two units to attack X-COM, massing, then attacking in a second wave.
 +
 +
* Beta2 https://www.youtube.com/watch?v=ymA41OrS5HE
 +
**OK, another behaviour update. This time regarding the Alien's use of SMOKE grenades and going prone to crawl forwards when under fire.
 +
**A few playtests of both vanilla and beta reveal that the aliens will start to use smoke grenades regularly after week 2 or once disruptor tech arrives in the aliens arsenal (tied to X-COM score and in lore presumably having got them from gangs or the CoS as they even appear on UFOs).
 +
**Anthropods and Skeletoids appear to have enough intelligence to throw smoke grenades before an attack then run in for the kill.
 +
**In the beta footage below (which gives the best example, though the behaviour is in vanilla too), a skeletoid even throws a smoke grenade behind one UFO door (making me thing they are about to emerge from there) but flanks around and exits via the other door before throwing another two smoke grenades and then attacking (and quickly being killed). Just one skeletoid performs this attack as (unknown to me) the aliens are massing in the UFO for another three waves of attacks. This starts from about 3:40 in the video ;)
 +
**At around 6:40 also note the skeletoid going prone and crawling towards the X-COM agents who are attacking it...
 +
**Finally at approximately 8:10, look how one of the agents successfully dodges not one, but two entropy missiles that the aliens have kept hidden till the end of the mission (i didnt even know they had started to equip them at this point). So entropy missiles can be dodged just as vehicles dodge missiles...
 +
 +
*https://www.youtube.com/watch?v=cXQBr77PsAo
 +
**Megapol does not fight back until a significant number of officers are dead (which is tied to the organisation relations)
 +
**Megapol spams officers that will group, throw grenades, attack, retreat, regroup and attack in another wave (much like the aliens)
 +
**Megapol uses stun and smoke grenades as well as standard explosives
 +
**Megapol buildings contain equipment that can be looted; even Elerium!!
 +
**Megapol uses it's own equipment, unless X-COM has sold alien weapons to the "city" in which case some Megapol officers carry disrupter weapons (not shown in this video but observed in other playthroughs)
 +
**X-COM agents can spot capturable equipment within a certain radius, even without LoS (Most likely a bug)
 +
*https://www.youtube.com/watch?v=HbScwE6u1DI
 +
** Marsec is very reserved in committing units, MarSec agents retreat from direct conflict and do not group and attack in waves like Aliens, CoS or Megapol
 +
** Marsec attempts to flank the player then blast them with missiles (I lose a squad in the video below whilst dealing with other Marsec units that are running from me to a second group of Marsec Agents that emerge from my left flank)
 +
** Marsec equipment is used by all Marsec units. They do not appear to purchase alien tech from X-COM like Megapol does.
 +
** Marsec will use Alien tech if they become controlled by the Aliens.
 +
*Found a behavior on the megaspawns, as usual they attack from afar, but when approached, quickly retreats. They will only stop retreating if they got away from the unit that approached them or when cornered, this is tested on realtime, in turn based however this doesn't apply
 +
**With regards to turn-based, they do appear to do the same, however there are some issues with their TUs and how much they can actually do. A retreat will only occur if they cannot fire at a unit first, if they fire their weapons they cannot retreat. Generally however, their movement is away from X-COM agents in TB Mode...
 +
**They also have an annoying habit of grouping together in vanilla... In Beta2 they don't group but are often surrounded by lots of Anthropods used as shields or near poppers that have been held back.
 +
*FilmBoy can you confirm this behavior of all aliens that can use grenades? In one of my test in realtime, I killed a bunch of them in a room, when I moved my agents in, there is this one alien that went yolo, and tossed a grenade in the room, blowing all the grenades in the floor, killing my entire squad in the process, as well as himself. However it doesn't apply with the room being empty, so was this a rare behavior in some sort?
 +
**In game versions with the nerfed AI it appears to be related to chance, the alien has a "random" factor that it will choose to throw a grenade in a room of explosive munitions or simply as a means to kill massed agents
 +
**In game versions with the Learning-AI if grenades have been good at killing agents previously, the aliens will use them more frequently, increasing the chance of them creating chain reactions as munitions go up. Aliens will also utilise the boomeroids "jump/travel" feature to attack around corners and through doors also
 +
**In short though, it all boils down to chance and circumstance as to whether or not grenade capable aliens kill your agents with grenades. Learnt behaviour only increases that chance on a player-by-player basis and only if the player has been vulnerable to grenades in previous actions, if not, the chance of a grenade being used is still low.
 +
**Things were different in Beta: Grenades were often used to spam X-COM once the aliens learnt through the extended AI how effective the action was and it was brutal... Couple that with Alien numbers far higher than vanilla (as it should be IMHO - this is an invasion) it's a recipe for disaster...
 +
**https://www.youtube.com/watch?v=WKvkHbzvgzg
 +
 +
===Unique to BETA (Does all of the above plus these behaviours too):===
 +
*Anthropods and Skeletoids will swarm together, attack in groups, then quickly retreat before agents have time to respond. I rarely encounter single units of these types in the Beta, if I do they are often trying to exit (see below) or looking for more Aliens to group up with.
 +
*Aliens will methodically move through through a map in groups of 2-5 until they find X-COM, they then retreat, CRY FOR HELP (which attracts other aliens of all types) and attack again this makes them hard to fight as you always face numbers of aliens and killing a few forces them to retreat and regroup. It's very "Cat and Mouse" and a joy to play for an experienced player but a nightmare for casual players who will find it too hard (Guess this is why such behaviour was removed)
 +
*If there are two or less Anthropods/Skeletoids on a map they will head towards the map exits and fall back to the cityscape, this doesn't end the mission as all other alien types remain until X-COM knocks them out or kills them, but it does allow the Aliens to keep foot soldiers in Mega-Primus for a longer time before they expire (as per the alien life cycle)
 +
*Cult of Sirius use EXCESSIVE amounts of incendiary weaponry spamming incendiary grenades and incendiary missiles of various types this is different to vanilla where they spam explosive weapons. The cult is a fearsome opponent as a result and their behaviour causes buildings to collapse as they burn around your agents; this often lags the game which may be why the CoS was changed to using Explosive weaponry? I wonder if BETA behaviour could be reintroduced now we have better CPUs (maybe as an option)
 +
*Aliens with disruptor weaponry will fire randomly in the direction they believe X-COM to be hiding (or have previously seen agents), other aliens using the covering fire of their colleagues will then attempt to flank agents and come in to kill from behind
 +
*Aliens SPAM brainsuckers; i've faced waves of the things from the first battle!
 +
*Aliens crouch, go prone and move around a lot more to use cover in a similar manner to the vanilla X-COM agents
 +
*As per the Vanilla release, in tactical missions relating to cityscape activity, spitters will retreat to obscure places of the map to hide when the number of aliens are low. However, if X-COM take more than a few minutes (in real-time) or around 10 turns (in TB) to find the spitters, they will retreat to an exit and use the cityscape to infect another building keeping the presence of aliens in the cityscape for longer. They may or may not travel to the same location as escaping Anthropods and Skeletoids so it is possible that missions in which X-COM does not clear the map will result in lots more alien incidents in the cityscape later, albeit with weaker alien numbers.
 +
*Spitters tend to group together en-masse (as the lore suggests that they can) and it is not uncommon to find five or more together
 +
*Aliens "tagged" with a tracker gun will try to escape from combat to the cityscape; it appears the intent was to allow for players to follow aliens around the city much in the same way we were meant to be able to follow the VIPs of organisations (for which the cells were created). However, the Spitter is NOT meant to be an intelligent creature, so this may be why in Vanilla they simply sit around in cover waiting to be found.
 +
*Brainsuckers will form in groups and rush at X-COM agents in waves
 +
*Aliens armed with Brainsucker launchers will, if failing to find X-COM quickly, fire off all their pods, wait for them to hatch, then follow the wave of brainsuckers towards X-COM agent areas and armed civilians/gang members/police.
 +
*Lone brainsuckers that cannot find another alien will attempt to leave the map to further alien infection of the city via the cityscape. This can result in alien activity missions in which there will only be a lone brainsucker, that can retreat again if not killed quickly. Forming a chain of alien activity missions across the cityscape until the brainsucker infects a civilian, VIP, X-COM or is killed; something that can be really frustrating if you are not quick to kill the alien. I guess this may be why the feature was removed from brainsucker behaviour but it's still pretty cool nonetheless and compliments the "cat and mouse" behaviour of other aliens in the beta.
 +
*Brainsuckers WILL attack armed civilians to control them (I love this feature, so much more realistic to lore) and then direct those civilians towards known X-COM locations. There is however a bug in which brainsuckers occasionally try to attack UNARMED civilians which is pointless apart from adding to the civilian casualty figures.
 +
*Brainsucked civilians or gang/police members that cannot form into groups will attempt to leave the map if they are injured and cause more alien incidents later. They can also trigger gang/police wars if a gang member is brainsucked and attacks a rival gang when returning to the cityscape
 +
*Brainsucked civilians or gang/police members that are "tagged" with a tracker can be used to follow organisations that are being infiltrated by the aliens as when returning to the cityscape it appears that "tagged" units will try to fall back to the nearest building owned by a parent organisation or attack a building hostile to that organisation. I've followed a brainsucked unit across the cityscape to attack one of my bases only minutes later, and having found more allies from the parent organisation before moving in!
 +
 +
*'''It appears from BETA play that the intent was to have a similar AI to X-COM for the aliens but it was drastically nerfed or removed in part by release to make play easier for newcomers to the game regardless of difficulty mode. -[[FilmBoy84]]'''
 +
 +
*Found an odd behavior of the poppers, in the demo version, they will hide, wait till anthropods or skeletpoids to pin down your agents before attacking, while in vanilla, they'll just attack you head on
 +
**Yes, the same behaviour is in Beta. It's a much more effective use of poppers by the aliens and not easy to combat for first-time players.
 +
**I guess this is why the behaviour was modified for some final release versions.
 +
**Versions with the partially working "Learning AI" do use this strategy, but only after week 6 by which time poppers are easily one shotted by devastator/disruptor fire... So it's rare to see it succeeding.
 +
**Best demonstrated under vanilla during battleship UFO investigations... Once you get through those tunnels and into the UFO entrance (but past the megaspawn) there are often poppers held in reserve there...
 +
*Agents, Aliens and Others will all turn to face nearby sounds such as footsteps of other units... Not just their cries... This allows them to spot enemies sooner. - Tested by leaving agents in one spot facing all to the SE of the map. When the aliens approached the agents turned automatically towards the sound of them moving. Some agents also used that prompt to look for cover and use it.
 +
*Agents that have wounds will move to cover and if equipped with a medkit AND a free hand will attempt to heal themselves if in Evasive/Cautious Mode. Aggressive Mode ignores this behaviour. If the agent does not have a free hand they do not reach for a medkit in their equipment.

Latest revision as of 16:27, 20 December 2022

Artificial Intelligence

The Tactical Game uses a sophisticated Al system to control non-player forces. The system will adapt to your tactics by learning from its actions. This adaptation process occurs after each Tactical Game is played. The computer analyses an experience data file in order to update its decision matrices. The Al does not cheat (ie it has no privileged information or abilities beyond that of a human player). The data files for the Al are not stored as part of a saved game, they are continually updated. You can exchange the files with other X-COM players in order to experience different tactics from the Al player. Ensure that you exchange all three of the relevant files that are located within the TACDATA subdirectory.

FilmBoy say that its working on UK CD release and not in US or some others, also its need phisical CD inserted and no use dosbox

below is scan of page from book X-COM Apocalypse: The Official Strategy Guide (Secrets of the Games Series) Paperback – August 26, 1997 by Dave Ellis Learning AI.jpg


Unit Behavior

A list of actions, abilities, reactions and more, within X-Com Apocalypse. All actions mentioned here are present in the final version release unless noted with Debug.

Agents on Normal or Safe behaviour settings on Vanilla and BETA will:

  • Hide behind other agents that are kneeling and shoot over their heads
  • Agents placed at a corner to a corridor will move back and forth between hiding "in cover" and exposing themselves around the corner to shoot/view
  • Agents jump over 1-tile "gaps" in floors if it gets them to cover
  • Agents will jump down a maximum of 1 tile if it gets them away from fire to another floor or if injured to get them to a safer place
  • Agents will strafe back and forth whilst moving in and out of cover, even along a line of kneeling agents and shooting over their heads
  • Agents will run away from fire
  • Agents with a partially "stunned" value will run out of smoke to avoid being "gassed" further, this means that they can expose themselves to weapons fire but minimise the risk of falling unconscious
  • Agents with no "stunned" value will remain in smoke to utilise it as cover though often go prone or kneel if both stances are selected
  • Agents equipped with trackers (beta only) or scanners will "enhance" the behaviour of other agents in their squad (No effect on other squads). For example, agents in cover will respond to a blip by moving around corners to look down corridors or into rooms.
  • Agents raise weapons in readiness in response to alien cries
  • Agents raise weapons in readiness in response to nearby explosions, civilian screams and the sound of burning
  • Agents respond to alien cries as per the documentation i have given in the relevant thread
  • In Tactical Missions relating to Cityscape activity, spitters will wander around, when there are more than two **mobile** aliens on the map, trying to kill civilians (their main function it appears) and sniping at X-COM. If there are few aliens on the map, spitters will try to hide, often in obscure places of the map and in smoke until agents find them.
  • In UFO recovery, spitters will frequently hide in the upper levels of the UFO trying to avoid engaging X-COM and not really being utilised by the aliens. If they do travel to the lower decks or outside it is with Anthropods or Skeletoid allies. This behaviour seems bugged; spitters are sitting ducks in UFO missions and should be more active IMHO having the AI waste them by sitting in the upper levels makes no sense.
  • Brainsuckers can appear on maps at the start of a mission without having hatched from a pod
  • Brainsuckers will run around the map until they find an X-COM agent, though they often "pause" and become inactive, this is likely a bug.
  • Brainsuckers will attempt to run and leap on to the first agent they encounter to brainsuck them
  • https://www.youtube.com/watch?v=YE0AXGppZtU
    • Brainsucker gets "stuck" and promptly shot after recovering from stun.
    • Agents strafing and hiding around corners
    • Brainsucker cry from the right of the screen (in darkness) allowing me to locate the last brainsucker and kill it winning the mission (cries can be used like this in vanilla, fortunately, my agent did not panic this time around as i sent him down a corridor alone).
    • Anthropods working alone and not in groups as they did in beta
    • Agents will react to alien sightings and fire whilst running, in this case saving me from a leaping brainsucker
  • Beta2 https://www.youtube.com/watch?v=_DvtnGSUsUU
    • Beta Footage in which the aliens sabotage their own brainsuckers by destroying the escape route to the cityscape for a lone brainsucker. Also shows Anthropods sending two units to attack X-COM, massing, then attacking in a second wave.
  • Beta2 https://www.youtube.com/watch?v=ymA41OrS5HE
    • OK, another behaviour update. This time regarding the Alien's use of SMOKE grenades and going prone to crawl forwards when under fire.
    • A few playtests of both vanilla and beta reveal that the aliens will start to use smoke grenades regularly after week 2 or once disruptor tech arrives in the aliens arsenal (tied to X-COM score and in lore presumably having got them from gangs or the CoS as they even appear on UFOs).
    • Anthropods and Skeletoids appear to have enough intelligence to throw smoke grenades before an attack then run in for the kill.
    • In the beta footage below (which gives the best example, though the behaviour is in vanilla too), a skeletoid even throws a smoke grenade behind one UFO door (making me thing they are about to emerge from there) but flanks around and exits via the other door before throwing another two smoke grenades and then attacking (and quickly being killed). Just one skeletoid performs this attack as (unknown to me) the aliens are massing in the UFO for another three waves of attacks. This starts from about 3:40 in the video ;)
    • At around 6:40 also note the skeletoid going prone and crawling towards the X-COM agents who are attacking it...
    • Finally at approximately 8:10, look how one of the agents successfully dodges not one, but two entropy missiles that the aliens have kept hidden till the end of the mission (i didnt even know they had started to equip them at this point). So entropy missiles can be dodged just as vehicles dodge missiles...
  • https://www.youtube.com/watch?v=cXQBr77PsAo
    • Megapol does not fight back until a significant number of officers are dead (which is tied to the organisation relations)
    • Megapol spams officers that will group, throw grenades, attack, retreat, regroup and attack in another wave (much like the aliens)
    • Megapol uses stun and smoke grenades as well as standard explosives
    • Megapol buildings contain equipment that can be looted; even Elerium!!
    • Megapol uses it's own equipment, unless X-COM has sold alien weapons to the "city" in which case some Megapol officers carry disrupter weapons (not shown in this video but observed in other playthroughs)
    • X-COM agents can spot capturable equipment within a certain radius, even without LoS (Most likely a bug)
  • https://www.youtube.com/watch?v=HbScwE6u1DI
    • Marsec is very reserved in committing units, MarSec agents retreat from direct conflict and do not group and attack in waves like Aliens, CoS or Megapol
    • Marsec attempts to flank the player then blast them with missiles (I lose a squad in the video below whilst dealing with other Marsec units that are running from me to a second group of Marsec Agents that emerge from my left flank)
    • Marsec equipment is used by all Marsec units. They do not appear to purchase alien tech from X-COM like Megapol does.
    • Marsec will use Alien tech if they become controlled by the Aliens.
  • Found a behavior on the megaspawns, as usual they attack from afar, but when approached, quickly retreats. They will only stop retreating if they got away from the unit that approached them or when cornered, this is tested on realtime, in turn based however this doesn't apply
    • With regards to turn-based, they do appear to do the same, however there are some issues with their TUs and how much they can actually do. A retreat will only occur if they cannot fire at a unit first, if they fire their weapons they cannot retreat. Generally however, their movement is away from X-COM agents in TB Mode...
    • They also have an annoying habit of grouping together in vanilla... In Beta2 they don't group but are often surrounded by lots of Anthropods used as shields or near poppers that have been held back.
  • FilmBoy can you confirm this behavior of all aliens that can use grenades? In one of my test in realtime, I killed a bunch of them in a room, when I moved my agents in, there is this one alien that went yolo, and tossed a grenade in the room, blowing all the grenades in the floor, killing my entire squad in the process, as well as himself. However it doesn't apply with the room being empty, so was this a rare behavior in some sort?
    • In game versions with the nerfed AI it appears to be related to chance, the alien has a "random" factor that it will choose to throw a grenade in a room of explosive munitions or simply as a means to kill massed agents
    • In game versions with the Learning-AI if grenades have been good at killing agents previously, the aliens will use them more frequently, increasing the chance of them creating chain reactions as munitions go up. Aliens will also utilise the boomeroids "jump/travel" feature to attack around corners and through doors also
    • In short though, it all boils down to chance and circumstance as to whether or not grenade capable aliens kill your agents with grenades. Learnt behaviour only increases that chance on a player-by-player basis and only if the player has been vulnerable to grenades in previous actions, if not, the chance of a grenade being used is still low.
    • Things were different in Beta: Grenades were often used to spam X-COM once the aliens learnt through the extended AI how effective the action was and it was brutal... Couple that with Alien numbers far higher than vanilla (as it should be IMHO - this is an invasion) it's a recipe for disaster...
    • https://www.youtube.com/watch?v=WKvkHbzvgzg

Unique to BETA (Does all of the above plus these behaviours too):

  • Anthropods and Skeletoids will swarm together, attack in groups, then quickly retreat before agents have time to respond. I rarely encounter single units of these types in the Beta, if I do they are often trying to exit (see below) or looking for more Aliens to group up with.
  • Aliens will methodically move through through a map in groups of 2-5 until they find X-COM, they then retreat, CRY FOR HELP (which attracts other aliens of all types) and attack again this makes them hard to fight as you always face numbers of aliens and killing a few forces them to retreat and regroup. It's very "Cat and Mouse" and a joy to play for an experienced player but a nightmare for casual players who will find it too hard (Guess this is why such behaviour was removed)
  • If there are two or less Anthropods/Skeletoids on a map they will head towards the map exits and fall back to the cityscape, this doesn't end the mission as all other alien types remain until X-COM knocks them out or kills them, but it does allow the Aliens to keep foot soldiers in Mega-Primus for a longer time before they expire (as per the alien life cycle)
  • Cult of Sirius use EXCESSIVE amounts of incendiary weaponry spamming incendiary grenades and incendiary missiles of various types this is different to vanilla where they spam explosive weapons. The cult is a fearsome opponent as a result and their behaviour causes buildings to collapse as they burn around your agents; this often lags the game which may be why the CoS was changed to using Explosive weaponry? I wonder if BETA behaviour could be reintroduced now we have better CPUs (maybe as an option)
  • Aliens with disruptor weaponry will fire randomly in the direction they believe X-COM to be hiding (or have previously seen agents), other aliens using the covering fire of their colleagues will then attempt to flank agents and come in to kill from behind
  • Aliens SPAM brainsuckers; i've faced waves of the things from the first battle!
  • Aliens crouch, go prone and move around a lot more to use cover in a similar manner to the vanilla X-COM agents
  • As per the Vanilla release, in tactical missions relating to cityscape activity, spitters will retreat to obscure places of the map to hide when the number of aliens are low. However, if X-COM take more than a few minutes (in real-time) or around 10 turns (in TB) to find the spitters, they will retreat to an exit and use the cityscape to infect another building keeping the presence of aliens in the cityscape for longer. They may or may not travel to the same location as escaping Anthropods and Skeletoids so it is possible that missions in which X-COM does not clear the map will result in lots more alien incidents in the cityscape later, albeit with weaker alien numbers.
  • Spitters tend to group together en-masse (as the lore suggests that they can) and it is not uncommon to find five or more together
  • Aliens "tagged" with a tracker gun will try to escape from combat to the cityscape; it appears the intent was to allow for players to follow aliens around the city much in the same way we were meant to be able to follow the VIPs of organisations (for which the cells were created). However, the Spitter is NOT meant to be an intelligent creature, so this may be why in Vanilla they simply sit around in cover waiting to be found.
  • Brainsuckers will form in groups and rush at X-COM agents in waves
  • Aliens armed with Brainsucker launchers will, if failing to find X-COM quickly, fire off all their pods, wait for them to hatch, then follow the wave of brainsuckers towards X-COM agent areas and armed civilians/gang members/police.
  • Lone brainsuckers that cannot find another alien will attempt to leave the map to further alien infection of the city via the cityscape. This can result in alien activity missions in which there will only be a lone brainsucker, that can retreat again if not killed quickly. Forming a chain of alien activity missions across the cityscape until the brainsucker infects a civilian, VIP, X-COM or is killed; something that can be really frustrating if you are not quick to kill the alien. I guess this may be why the feature was removed from brainsucker behaviour but it's still pretty cool nonetheless and compliments the "cat and mouse" behaviour of other aliens in the beta.
  • Brainsuckers WILL attack armed civilians to control them (I love this feature, so much more realistic to lore) and then direct those civilians towards known X-COM locations. There is however a bug in which brainsuckers occasionally try to attack UNARMED civilians which is pointless apart from adding to the civilian casualty figures.
  • Brainsucked civilians or gang/police members that cannot form into groups will attempt to leave the map if they are injured and cause more alien incidents later. They can also trigger gang/police wars if a gang member is brainsucked and attacks a rival gang when returning to the cityscape
  • Brainsucked civilians or gang/police members that are "tagged" with a tracker can be used to follow organisations that are being infiltrated by the aliens as when returning to the cityscape it appears that "tagged" units will try to fall back to the nearest building owned by a parent organisation or attack a building hostile to that organisation. I've followed a brainsucked unit across the cityscape to attack one of my bases only minutes later, and having found more allies from the parent organisation before moving in!
  • It appears from BETA play that the intent was to have a similar AI to X-COM for the aliens but it was drastically nerfed or removed in part by release to make play easier for newcomers to the game regardless of difficulty mode. -FilmBoy84
  • Found an odd behavior of the poppers, in the demo version, they will hide, wait till anthropods or skeletpoids to pin down your agents before attacking, while in vanilla, they'll just attack you head on
    • Yes, the same behaviour is in Beta. It's a much more effective use of poppers by the aliens and not easy to combat for first-time players.
    • I guess this is why the behaviour was modified for some final release versions.
    • Versions with the partially working "Learning AI" do use this strategy, but only after week 6 by which time poppers are easily one shotted by devastator/disruptor fire... So it's rare to see it succeeding.
    • Best demonstrated under vanilla during battleship UFO investigations... Once you get through those tunnels and into the UFO entrance (but past the megaspawn) there are often poppers held in reserve there...
  • Agents, Aliens and Others will all turn to face nearby sounds such as footsteps of other units... Not just their cries... This allows them to spot enemies sooner. - Tested by leaving agents in one spot facing all to the SE of the map. When the aliens approached the agents turned automatically towards the sound of them moving. Some agents also used that prompt to look for cover and use it.
  • Agents that have wounds will move to cover and if equipped with a medkit AND a free hand will attempt to heal themselves if in Evasive/Cautious Mode. Aggressive Mode ignores this behaviour. If the agent does not have a free hand they do not reach for a medkit in their equipment.