Alien psionics - how does the game determine whether or not it can attack me?

[Solarius Scorch]

more fair is line of sight req for PSI makes the game less hard.

In the beginning, sure, but this feature benefits you as well - I believe more. I've been cleaning Cydonia multiple times using almost solely mind-controlled units. With LOS psionics, this is not possible.

[kikimoristan]

yeah is equally fair for everyone. psionics does have a range though. 

[7Saturn]

yeah is equally fair for everyone. psionics does have a range though.

I find that quite usefull, as you can increase your probabilty to succeed in any mind attack by closing in on the target. Even with psi-ability 20 you could have success, provided, your soldier is strong enough. Helps to train rookies on their way to mind domination! 

[Warboy1982]

depending on difficulty level aliens will remember units for a certain amount of turns. what that means is if you been spotted and you run away you will still get MCd for a bunch more turns. more fair is line of sight req for PSI makes the game less hard.

this difficulty based memory gets used by aliens for various things like making decisions where to go if to shoot in a certain direction or throw a grenade etc.

difficulty doesn't factor into the alien memory... no idea where you got that from.

[Align]

I suppose you could say the difficulty "level" of the alien species matters - Ethereals are more intelligent and "remember" for more turns. Though I don't think that holds up with Mutons...

[kikimoristan]

intelligence stats that is is the memory right?

[Align]

Right, although now that I check units.rul it's all over the place. Sectoids get between 3-8 intelligence according to rank, Floaters get 4-8 (so +1 compared to Sectoids, except commanders at 8), Snakemen 2-6, Mutons 2-4, Ethereals unsurprisingly 6-8 (which helps make their psi so dangerous despite their psi stats being mediocre compared to carefully vetted XCOM soldiers).

[kikimoristan]

8 means they remember you for 8 turns?

[Align]

That I don't know. I would guess so, but also guess that it's like primed grenades - it's 8, where your turn and alien turn are counted as 2 turns. So 3 int aliens barely remember your position after spotting you their last turn. Though if I'm guessing right, that would also mean terror missions leave you slightly less vulnerable to psi lock-on, since civilians get a turn...

[mrxian]

I'm pretty damn sure that in vanilla, they'd target your entire team as soon as they saw any member of your team.

I haven't tested OpenXcom extensively yet, but it seems to be similar, with the psi attacks happening far behind the front line against soldiers I thought weren't spotted.

I'm really torn here - turning on psi line of sight basically removes enemy psi from the game (They choose to fire their weapons over using psi, I guess), and keeping it off means I have very little defense against psi and must resort to cheap tactics to work against it.

[7Saturn]

I'm pretty damn sure that in vanilla, they'd target your entire team as soon as they saw any member of your team.

Of that I'm most sure. Best example: You have one Tank an one soldier in a base entrance area. The tank is blocking the elevator, so nothing can get through. The soldier is placed in the far corner of the entrance area upstairs. It still gets psi-attacked, even when there simply can't be a los for the aliens. The only can see the tank, which they never attack with psi, but they still find the soldier hiden outside their view.