XCOM 2
A Better ADVENT 2
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DerBK  [developer] 5 Nov, 2016 @ 6:02am
AI Changes
-- Global AI parameter changes --
These changes are to global parameters of the vanilla AI, not unit specific ones.

DownThrottleUnitCount
The vanilla patrolling AI starts to steer unrevealed pods away from the XCOM team if it has a certain minimum number of engaged already. This number has been increased massively, therefore almost eliminating this unnecessary AI shackle.

MaxEngagedEnemies
Depending on the difficulty, vanilla XCOM applies a limiter to the number of engaged enemies. Only on Legendary, this shackle was removed. A Better ADVENT removes it for all difficulties.

FallbackChance, UnitInFallbackRangeMeters
When a unit is alone in his pod, it will search within a certain range for another pod to flee to. If he stays or flees is left to a random roll against a percentage. The range in which a unit looks for a potential new pod has been increased, as has the chance to flee.

DefaultIdealRange
The default distance that aliens try to keep if they don’t have other things to consider (like weapon ranges or unit specific values). This value has been slightly increased.

Curr_Tile_Linger_Penalty
When deciding where to move, XCOM decides how “valuable” every tile in range is, then uses the best. To promote alien movement, it penalizes the current tile it stands on. This penalty has been lowered a lot, so aliens actually stay in place if they found a good one.

Calc_Mid/High_Cover_Factor
When deciding on how valuable tiles are, cover applies a factor to this weight. These factors have all been increased considerably. The old factors were 1.0 for mid cover (yes, really) and 1.1 for full cover. Leaders had a special treatment that made them value full cover at a factor of 2.5. Or in other words, other than pod leaders, enemies basically do not care much about cover in vanilla XCOM.
A Better ADVENT changes these values to 1.5 for mid cover, 2.5 for high cover and 3.0 for pod leaders and high cover.

MoveWeightProfiles
There are several Profiles that set up how an alien decides how valuable tiles are for movement. Factors are things like cover, distance to enemies, flanking shots possible, allies in line of sight and a couple others. These have been tweaked, again mostly with regards to cover, but also in a few other areas where the value looked a bit off.

MoveWeightProfile: MimicBeacon
One of those profiles takes over whenever there’s a Mimic Beacon in sight. Before, this profile took no regard at all for the aliens safety, which is just unrealistic. It has been changed so that aliens still go for the Mimic Beacon with their actions, but keep on using cover, staying apart from each other and don’t run into flanks.
Last edited by DerBK; 5 Nov, 2016 @ 6:05am
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DerBK  [developer] 5 Nov, 2016 @ 6:06am 
-- Improvements to Overwatch --
These changes aren’t global, but they are not unit specific either. They have been integrated into all behavior trees introduced by A Better ADVENT where applicable. Only after the alien that is about to shoot made sure that none of the Priority Shots is available and that no Overwatch Override is happening, it will run into the vanilla routines for targeting and overwatching.

Overwatch Override
The Overwatch Override is a completely new routine that checks if a unit is better off going into Overwatch instead of taking crappy shots. It also provides a random chance to Overwatch even on decent shots to keep the enemy guessing. Finally, it will make an enemy that is fully alerted, but currently not seeing any targets, consider going into Overwatch and letting the targets come to him. It works by checking the highest available hit chance and making a random roll against a percentage. This percentage is further influenced by the number of teammates that are already on Overwatch. If the roll is successful, the alien goes into Overwatch. The exact values are:
Highest Chance to Hit < 10% --> Chance to Overwatch = 90%/75%/50%
Highest Chance to Hit < 25% --> Chance to Overwatch = 75%/60%/40%
Highest Chance to Hit < 50% --> Chance to Overwatch = 30%/20%/10%
Highest Chance to Hit < 75% --> Chance to Overwatch = 10%/5%/1%
No targets in sight --> Chance to Overwatch = 75%/75%/75%
(The first value is for no other overwatching teammates, the second for one other overwatcher, the third for every one after that)

Overwatch VIP and Evac
Vanilla AI has fairly high chances to Overwatch when a VIP is near or when an Evac zone is in sight. These chances have been lowered.
Last edited by DerBK; 5 Nov, 2016 @ 6:06am
DerBK  [developer] 5 Nov, 2016 @ 6:07am 
-- Improvements to Targeting --

Priority Shots
Five types of potential shots now take priority over the vanilla targeting routine. They are:
- Flanked Shots. If a unit has a target flanked, he should take that shot. No considering about other targets, no raising of Zombies, just pop that guy that’s standing in the open. This also has a higher priority than the Overwatch Override.
- Kill Shots. If a unit could potentially kill someone, that’s worth trying. Making XCOM lose a soldier is worth more than wounding 5 of them.
- Sure Shots. Aliens have a fairly lousy chance to hit, so whenever they get a clean one, they better take it. Everything with a hitchance > 80% is considered a “Sure Shot” in this context.
- Shots on Suppressors.
- Shots on Overwatchers.

Panic fix
Enemies in vanilla XCOM don’t target panicked units unless there’s nothing else to shoot – even when that target is being flanked. This behavior has been removed, shooting at panicked units is absolutely something that enemies should do.
DerBK  [developer] 5 Nov, 2016 @ 6:07am 
-- Improvements to ability use --

Most enemies use their abilities on cooldown whenever they can. Their decision tree sets up a very binary list of priorities and the first thing that can be used will be.
A Better ADVENT links some abilities to other triggers, modifying these priorities if certain conditions are met. These changes aren’t global, they are customized per unit.
When an alien has only bad shots available, it will consider other options more strongly than it would otherwise.
Examples for specific changes:
- Sectoids that have only bad shots available will go for Mindspin, hoping to panic someone out of their full cover into a more vulnerable spot
- Demolitionist Troopers and Mutons use their grenades more aggressively. If they don’t have a good shot on anyone, they will use their grenade on single targets as well, hoping to destroy their cover.
- Mutons may also use Suppress in that situation instead.
DerBK  [developer] 5 Nov, 2016 @ 6:08am 
-- New AI decision trees --

The behavior of units in combat is governed by decision trees. Almost all enemies have gotten new AI trees, including the vanilla units.
The following AI trees stay unmodified: Gatekeeper, Faceless, Psi Zombie, Andromedon Shell and Vanilla Chryssalid. The Gatekeeper AI is good and doesn’t really need changing. The other units are simple melee fighters that don’t have anything interesting going on.
All others have at least the Targeting and Overwatch improvements worked into their AI trees. Some also had a few of their priorities concerning ability use switched around to make a bit more sense.
Many of the AI trees also got a movement profile that better fits their role in combat. This movement profile takes priority over any jobs assigned to a unit.
A Better ADVENT assigns new AI trees to the following 15 unit types: Trooper, Captain, Stun Lancer, Shieldbearer, MEC, Avatar, Turret, Andromedon, Archon, Berserker, Codex, Muton, Sectoid, Viper, Sectopod.
Examples for specific changes:
- Moved “Mark Target” priority down a bit. Advent Captains do no longer waste flank shots or sure shots by spending their turn with marking.
- Stunlancers are no longer pure melee units. They will use their guns to take any opportunity shots they come across. They will also sometimes randomly decide to use their gun instead of the stun baton.
- Turrets will no longer waste their second action. Most often, they will choose Overwatch if they don’t find a particularly good shot to take.
- Codices are more defensive, they will use their Teleport to keep distance and stay in cover, taking shots from there.
- Sectoids have a lesser probability to use Psi Reanimation and won’t use it at all if they have someone flanked.
- Shieldbearers no longer use their shield when they are already shielded due to another Shieldbearer on the field.
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