Author Topic: Alien psi behavior question  (Read 1067 times)

Offline cevaralien

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Alien psi behavior question
« on: August 20, 2020, 07:08:32 pm »
I developed a psi-suit for my mod, that allows the user to resist psi attacks. I don't want to modify the psi-strength stat, so, i use the psiDefence tweak. The question is:

Does aliens continue psi attacking the soldier with less psi strength if the armor have a high psiDefence?

After the mod, i confronted the Ethereals, but they don't psi-attacks me.

Notice that i changed the psi accuracy of the ALIEN_PSI_WEAPON and the "PSI_AMP":
Quote
   - type: ALIEN_PSI_WEAPON
    hitSound: 36
    battleType: 9
    tuUse: 40
    accuracyMindControl: -10
    accuracyPanic: -10
    costMindControl:
      energy: 20
    costPanic:
      energy: 10
    flatRate: false
    recover: false

Another tweak is that my soldiers psi strength are limited at 50, just like psi-skill.

The Sectoid Leader have PST 40 / PSK 50, the Commander have 40/60, while the Ethereals Soldiers are 50/40, leaders 50/50 and commanders 50/60 (units.rul).

I know that equation for psi attack and defense from ufopaedia. I put them on librecalc to evaluate the probability of MC and Panic and it works. I don't know if the aliens have a limitation based on this evaluation and for that reason, they don't attacks me.

Offline The Reaver of Darkness

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Re: Alien psi behavior question
« Reply #1 on: August 21, 2020, 05:02:17 pm »
A 50/60 alien with a -10 psi attack accuracy will have difficulty attacking one with 50 psi strength already; with any significant amount of psi defense they won't be able to attack at all.

You said you have a tool for calculating probability, well make sure you have accuracy factored in. -10 accuracy seems to do roughly -20% chance of success in my small amount of data collection.

As a rule of thumb, you can multiply psi strength and psi skill to get psi attack, and you can multiply (psi strength + 20% of psi skill) by 50 to get psi defense. Your Ethereal Commander would have 3000 psi attack, and your soldier with 50 psi strength and no psi skill would have 2500 psi defense, while a soldier with 50/50 would have 3000 psi defense. The Ethereal Commander would need to be at close range to succeed in a -10 accuracy attack, especially if the soldier had high psi skill.
« Last Edit: August 21, 2020, 05:06:39 pm by The Reaver of Darkness »

Offline cevaralien

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Re: Alien psi behavior question
« Reply #2 on: August 23, 2020, 06:50:03 pm »
Ok, i understand. That is just i'm looking for. I don't want to nerf the game with psi attacks from any side, but i don't want to eliminate at all or use LOS.

After some test, i notice that Ethereals begun to attacks my psi soldiers (40 or more of PST). They ignore my operatives using psi-armor, althought the PST is lower, so, the PsiDefence of the armor is working without the need to rise the PST stat.

Some attacks succeded, but not all.


Offline The Reaver of Darkness

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Re: Alien psi behavior question
« Reply #3 on: August 24, 2020, 04:11:51 am »
Any one psi alien will lose all of its psi effectiveness over a relatively small range of growing psi defense. Too low and it can succeed from the far end of the map every time. Too high and it never even makes an attempt. I find the way to make psi defense work more smoothly over a larger range of possible values is to have multiple levels of psi power in one given crew. Firstly, you probably want to set a psi strength minimum in your soldiers in addition to the maximum. A soldier with 5 psi strength can be mind-controlled from across the map by the weakest psi aliens. A good minimum might be half the maximum.

You figure out which ranks will be about what psi power level. For example, let's say we want the following:
Ethereal Soldier: good psi against psi-weak soldiers only
Ethereal Leader: mostly good psi, but high psi strength or psi armor weakens it, and both block it out completely
Ethereal Commander: the top psi defense weakens its psi, but it can still get through especially at close range

Then you'd just set about a guesstimate and check operation setting each unit's psi power and presenting them targets of the psi defense value you expect them to be less able to (but still able to) psi attack. If it's done right (and assuming they use the vanilla alien psi weapon) then they should be able to succeed with panic often but generally not mind control. They should also fail the attack fairly often, or be less likely to try. These are all signs you can use to determine when their success rate is falling away.

The vanilla psi gives Panic Unit a +20 accuracy bonus over Mind Control. I'm not sure what the 20 actually represents (might be a 20% increase in psi power) but in my own tests it seems to bump the success chance up by roughly 40% in times when it may or may not succeed. So for example an alien with ~20% chance to succeed with mind control might have ~60% chance to succeed with panic unit. I like to make the gap even larger, giving mind control a -10 accuracy penalty so that there's a fairly substantial range within which they will frequently succeed with panic yet fail or not even bother with mind control. Using this method plus (usually) 3 types of psi alien on a psi deployment, I find I am able to tweak the psi attack and defense values to the point that every bit of psi defense you gain makes a difference.

Offline cevaralien

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Re: Alien psi behavior question
« Reply #4 on: August 25, 2020, 03:18:31 am »
It's an interesting way to do the job. In fact, i my case is working similar.

The big changer in the psi attack/defense equation is the random number from 0 - 55. If you put the PST limits of soldiers and aliens at or more than 70, that random number begun to be less important, but, with the vanilla levels of Sectoids psionics, for example, with vanilla soldiers at 70 PST the game begun to be a piece of cake.

For that reason i define these levels of PST/PSK, combined with changes in accuracy. These changes allows some of the proposals that you do. For example, Ethereal Soldiers have a low probability of succeed, because the random number must be over 40 for a mind control, but, the Leaders requires less and the Commander much less, towards a soldier with PST/PSK 40/50. Even 50/50 is possible to succeed, but, the probability is too low.

i do the same with accuracy, i used -10% for MC and it is doing the job well. For example, my soldiers are not psi perfect when attacks the Muton, so, this help to minimize the abuse of psi attacks.

I haven't succeded with a Ethereal yet, but i haven't tried so much.