Mind Control and LoS

[alienjon]

Coming back for a campaign (first time in a few years) and progressed to the point of higher-level sectoids with mind control abilities.  I recall from the past (or at least thought) that psionics could only occur if an enemy has line of sight (not necessarily the alien with the mind control capabilities, but any enemy in line of sight of any friendly would allow a psi-capable alien to take advantage of).  I'm finding that this doesn't seem to be the case as I've been regularly on the receiving end of psionic attacks without any apparent enemy nearby.  As an example, I'm currently in a landed very large UFO mission and after only a few turns it seems that I'm constantly being barraged by psi attacks, even though the entire outside of the UFO has been cleared (I'm progressing inward, at this point, but haven't actually entered the UFO yet).

I looked online and the only info I can find is from the wiki, which states:

Alien Psionics Targeting

If any of your squad members, even a HWP, is visible to any alien during the Alien Turn, every member of your squad is at risk of attack from any psionic aliens, regardless of whether the spotter is psionic.

It should be noted that once you pass Turn 20, or if there are only 1 or 2 aliens left on the map, all of your squad members and their locations are revealed to the AI. This means you can expect a steady stream of psionic attacks after that turn if there any of the remaining aliens are capable of Psionic attack.

I may be about turn 20 now, but this has been going on for turns well before turn 20.  Did OpenXcom change the rules on this, or am I missing something obvious?

[7Saturn]

As far as I know, it is also sufficient to be »remembered«. On alien has seen someone of your team, and remembers that one for two turns or so. Maybe in combination, that leaves you at the disadvantage all the time. But I do remember that behavior from original X-COM as well (which is the one thing, that makes psi really unfair in the beginning, especially on the first terror mission, if it is with Sectiods: you are constantly screwed with no means of retaliation at all).

[Empiro]

Yeah, that's always been a huge problem when they start panicking your guys in the back of the Skyranger. There's no way they could have seen those folks at all.

I don't know if it's possible to make these two mods:

• Make it so that the aliens can only target soldiers they see that turn, just like you. No targeting of "remembered" soldiers.
  
• Make it so that you can only target entities your own (permanent) soldiers see. i.e. get rid of chain controlling, where you control one alien to scout and reveal more, and then control them, and so on.

I think having both would go a long way to make Psi/MC more balanced for players and less cheaty for aliens.

[cptelerium]

which is the one thing, that makes psi really unfair in the beginning, especially on the first terror mission, if it is with Sectiods: you are constantly screwed with no means of retaliation at all).

My top list of things that scare me as overpowered and "unfair"  (but war is never fair...) in Xcom:

1. this (MC by invisible enemies)

2. blaster bombs, suicidal style

3. 1-shot plasma kill of best solider even though he had flying armour and full HP

For 1 I guess just ruuushing it works (and heavy smoke around everyone for first 3-6 rounds + scouting ahead with tank), and too weak guys eventually die leaving more resistant as natural selection (still it's a R.I.P with big ufo sectoids and most ethereals)

For 2 also rushing especially if you get to leader/commander of who ever has B.L. in big UFOs, if he is close he usually doesn't fire (no suicide)

For 3, well that's life.

[Countdown]

Hi alienjon, I'm actually returning to the game after a couple years away as well. MC and LOS is something I've tested quite a bit and started a thread on back in 2016.

What I found was that aliens can attack any soldiers that have been spotted and are "remembered" as 7Saturn said. But they do have to have spotted them at some point. If they have been in the back of the skyranger and never seen by an alien or one of your mind controlled soldiers, then they can't be the target of psi attacks (until the turn 20 rule comes into effect of course).

Yeah, that's always been a huge problem when they start panicking your guys in the back of the Skyranger. There's no way they could have seen those folks at all.

That isn't actually the case. They have to have seen them at some point. Maybe they were spotted by one of your soldiers when they were mind controlled, or an alien was near enough the open door of the skyranger. But aliens can't launch psi attacks if they've never spotted the soldier.

• Make it so that you can only target entities your own (permanent) soldiers see. i.e. get rid of chain controlling, where you control one alien to scout and reveal more, and then control them, and so on.

I like this idea though since infinitely chaining psi attacks from alien to alien is so cheesy. Alternatively, you can just change the ruleset to make psi amps require line of sight.

[The Reaver of Darkness]

Mind control was never limited by line of sight in the original game, but openxcom offers that as an option. Just turn on the UFO Extender mod for Psionic LOS.

[Empiro]

Reviving this a bit, but could there be an intermediate setting for this: aliens can use PSI attacks without direct line-of-sight from the caster to the target. However, it can only done on targets that aliens actually spotted this turn, and not any of the "if one soldier is seen then all are targets" or "aliens automatically see everyone after turn 20" BS. Aliens move around randomly enough that I don't expect the PSI user to actually see their target, but targeting guys in the middle of your craft is just some next level crap.

I think the most balanced approach would be to require direct Line-of-Sight for player users to the target, and allow aliens to use PSI if any of their units directly and actively see the target.

[Meridian]

Yes, everything can be done. Someone just has to do it

To be more helpful, one would have to give/mod minimum intelligence value to all aliens.

and not any of the "if one soldier is seen then all are targets"

Anyway, I am replying mainly because of the myth above.
This was not true in the original and is also not true in openxcom.

Aliens have to "know about you" to use psi, which can happen only by actually seeing you (same turn or earlier, depending on intelligence), or by "knowing about (not seeing) everyone at turn 20, sometimes at turn 10".

[AlesiSanchez]

I am confused by this mechanic, I have just started a terror mission, spotted two aliens, but I'm 99% certain they did not see the guy they subsequently sent beserk because he was within the middle of a smoke cloud, was not spotted and was hit at the end of the 2nd turn (after he first exited skyranger into smoke and shot at an alien someone else spotted - he never left what I'm 99% sure was invisible area of the smoke). So I have no idea how they "knew about" him. I think he did fire at and hit one of the aliens (from inside smoke).

[Meridian]

Hitting an alien also makes you spotted.

https://github.com/OpenXcom/OpenXcom/blob/master/src/Battlescape/ProjectileFlyBState.cpp#L794

[AlesiSanchez]

Thank you so much. I see your comments everywhere helping out (obviously in addition to your mods!). Thank you sir.

Do rockets and grenades count as 'hitting' or does 'indirect' fire keep you hidden? 

[psavola]

As I read the code with my limited understanding, indirect fire (grenades, splash damage from rockets, blasters, etc.) should not trigger this. However, if you fire a rocket and it hits the target directly, at least then it get triggered. This is why in some cases (and with some specific sniper/spotter mods), you may want to target a ground square rather than enemy unit with your indirect fire.

I suppose apparently also a melee attack doesn't trigger this (if the unit was facing another way and didn't react and notice you visually). This was a somewhat surprising find for me.

[AlesiSanchez]

I bow in appreciation gents. 

[Meridian]

As I read the code with my limited understanding, indirect fire (grenades, splash damage from rockets, blasters, etc.) should not trigger this.

Nope.
Grenades, splash from rockets, etc. trigger it too.

https://github.com/OpenXcom/OpenXcom/blob/master/src/Battlescape/BattlescapeGame.cpp#L719

[psavola]

Nope.
Grenades, splash from rockets, etc. trigger it too.

https://github.com/OpenXcom/OpenXcom/blob/master/src/Battlescape/BattlescapeGame.cpp#L719

I stand corrected. It seems that I was correct on the part that stunning enemies don't get you spotted, though, so at least an indirect hit (that doesn't kill the enemy) doesn't count.