Enemies are afraid to attack ancient liches

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Elfnet
Posts: 6
Joined: September 20th, 2018, 12:09 am

Enemies are afraid to attack ancient liches

Post by Elfnet » August 13th, 2019, 9:22 pm

(1.14.7, Windows version)

When I played the Secrets of the Ancients campaign, on unpleasant (normal) difficulty, certain enemies weren’t ever tried to attack full health ancient liches.

The ancient lich is a powerful enemy, but for example in the scenario 19 (Lava and Stone), my lich just stood in place and trolls were afraid to attack. I killed at least half a dozen of them (one in every turn), the ancient lich basicly single handedly blocked half of the map and level 1 trolls just never attacked him, even when 4 of them were sit right next to it.

I didn’t checked all enemies, but in the last mission (scenario 21; Against the World) knights also didn’t tried to attack a full health ancient lich, but when his health were lowered a bit, they eventually attacked. Especially strange, that melee units weren't attacked (the primary ranged lich), while ranged enemied did.


(I understand that attacking a significanty stronger enemy is basicly suicide, so the AI maybe just didn't want to loose units, but other units, like zombies do suicidal wave attacks, chipping down health (even the cost of their life) and the enemies in the attached file never went on their business either (ignoring the lich and going for the towns or other enemies), like the AI in a strategic level tried to attack, but something in the units code prevented them to do so.

Or is this intentional and meant to be abused in easy difficulty?

[The attached file is in hungarian, but otherwise legit]
Attachments
AŐT-Láva és Kő visszajátszás.gz
The problem can be seen in turn 21 to turn 31 with the lower right side ancient lich.
(48.02 KiB) Downloaded 51 times

otzenpunk
Posts: 56
Joined: February 11th, 2018, 5:32 pm
Location: Hamburg / Germany

Re: Enemies are afraid to attack ancient liches

Post by otzenpunk » November 12th, 2019, 12:18 pm

Elfnet wrote:
August 13th, 2019, 9:22 pm
When I played the Secrets of the Ancients campaign, on unpleasant (normal) difficulty, certain enemies weren’t ever tried to attack full health ancient liches.
That's because of the lich's drain attack. Attacking an ancient lich with a weak melee attack has a high probability to leave him with more hitpoints than he had before, or if he's got full health, it just stays like it is. So ancient liches are basically invulnerable to many lvl1 or even lvl2 units, especially when they're as bad at defending as trolls. The AI recognizes that and doesn't even try.

Drain doesn't effect the lich's ranged attacks, though. So it is possible to wear them down by suicidal attacks from, for example, mages or orcish archers.
I didn’t checked all enemies, but in the last mission (scenario 21; Against the World) knights also didn’t tried to attack a full health ancient lich, but when his health were lowered a bit, they eventually attacked.
That's also a rational decision by the AI. It's because how the Wesnoth battle system works. The ancient lich has 4 strikes with his drain, but when the knight strikes first with his lance, three of the lich's strikes happen after the two of the knight. This means, when the lich's health is low enough, it is possible and not totally unlikely for the knight to kill him, and his one drain wouldn't matter that much. But if he's got more hitpoints than two successful lance strikes can possibly deduct, he will do his three drain attacks afterwards and that's shifting the balance against the knight again. (Note, that the lance assault doubles damages for both combatants, doubling the drain as well.)

Elfnet
Posts: 6
Joined: September 20th, 2018, 12:09 am

Re: Enemies are afraid to attack ancient liches

Post by Elfnet » November 12th, 2019, 3:32 pm

I understand the thinking behind why the AI do this, but it can be easily exploited. The AI don't attack the lich because of fearing to waste the low level unit's life, thats okay, but they don't leave it and chase the other player units and because they don't attack (even when they themself are attacked), the problem never goes away.
A human can recognize that the solution is to suicide attack or leave it to stronger units, but the AI is just paralized.

otzenpunk
Posts: 56
Joined: February 11th, 2018, 5:32 pm
Location: Hamburg / Germany

Re: Enemies are afraid to attack ancient liches

Post by otzenpunk » November 12th, 2019, 5:56 pm

Elfnet wrote:
November 12th, 2019, 3:32 pm
I understand the thinking behind why the AI do this, but it can be easily exploited.
Of course it can. As well as you can exploit the AI attacking you wildly without paying much attention to terrain or time of day. The AI isn't particularly intelligent, that's why it most often has access to much more/better ressources than the player to even things out.
A human can recognize that the solution is to suicide attack or leave it to stronger units,
No, not necessarily. I definitely can think of situations, where you might not have strong units available to target an uber unit like an ancient lich, but you do have access to lots of cheap cannon fodder, just to keep him occupied for a while and prevent him from rampaging around killing your more valuable troops, until you cleared the rest of the map. (Or, in case of the AI, the player's turn limit runs out.)

Elfnet
Posts: 6
Joined: September 20th, 2018, 12:09 am

Re: Enemies are afraid to attack ancient liches

Post by Elfnet » November 13th, 2019, 1:12 am

I know BfW is extremely old (by todays standard) and thus limited, but there are even older strategy games (like Age of Empire II from 1999*) where the AI have a ton of custom goals and orders to play competently with different factions or units and balance out the main AI's stupidity and I assumed that Battle for Wesnoth is the same (since it is still regularly updated).

The problem with what you described (AI occupying the player's strong unit with weak cannon fodder to buy time) is, that this does (could) not work with either ways: a player with a lich can simply ignore the low level distracting opponents and move on (since killing everybody isn't needed to win), while the computer is passive - it doesn’t even try to surround the strong unit or blocking paths for slowing it down, they just sit and idle (so they only waste the player’s time, if the player want to waste time killing them all).


*: In the 2013 HD remaster they made the AoE2 AI even better, but they used the 1999 frameworks, so this isn’t about age.

Soliton
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Re: Enemies are afraid to attack ancient liches

Post by Soliton » November 13th, 2019, 10:43 am

The AI is limited by someone writing a better one. If you're interested in improving the AI that is very much appreciated. Even a special AI for this scenario would probably be interesting.
"If gameplay requires it, they can be made to live on Venus." -- scott

Elfnet
Posts: 6
Joined: September 20th, 2018, 12:09 am

Re: Enemies are afraid to attack ancient liches

Post by Elfnet » November 14th, 2019, 1:17 am

I am interested, but while I messed with some programming and game design in the past, my C++ coding skills are basically nonexistent (and sadly writing articles for my website currently consumes most of my free time).

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