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GB-10 AI weakness

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Level 8 Human Perruptor
Alignment: Lawful
Posted on November 27, 2010 at 11:59 pm

If any developers are reading this...

The AI is really bad about moving almost its entire army out of a city when you come near, causing the city's defensive strength to plummet.

For example, my army is approaching Tricca and the Companions got there first, so I sent them around behind to scout and raid the farms. The garrison was about 150/100, but suddenly it's 3/100 and the defensive strength dropped from several thousand to a mere 520.

Level 8 Human True Nerd
Alignment: Chaotic good
Location: Meran
Posted on November 28, 2010 at 12:59 am

If any developers are reading this...

The AI is really bad about moving almost its entire army out of a city when you come near, causing the city's defensive strength to plummet.

For example, my army is approaching Tricca and the Companions got there first, so I sent them around behind to scout and raid the farms. The garrison was about 150/100, but suddenly it's 3/100 and the defensive strength dropped from several thousand to a mere 520.


thats something that annoyed me too since i started playing Hegemony. I wish we (and the AI) could recruite some sort of militia that cannot leave the city and keeps the defensive strenght up a little, maybe they could arrange that the militia units suffer casualties when the walls are damaged and the garrison strength goes down with it as well. The downside would be that these units can not leave the city they are supposed to defend, so they also cant avoid mines to be captured, farms to be burned and other nice things the AI does to you. I hope the developers may think about something like this

Level 8 Human Contractor
Alignment: Good
Location: Toronto
Posted on November 28, 2010 at 8:59 pm

thats something that annoyed me too since i started playing Hegemony. I wish we (and the AI) could recruite some sort of militia that cannot leave the city and keeps the defensive strenght up a little, maybe they could arrange that the militia units suffer casualties when the walls are damaged and the garrison strength goes down with it as well. The downside would be that these units can not leave the city they are supposed to defend, so they also cant avoid mines to be captured, farms to be burned and other nice things the AI does to you. I hope the developers may think about something like this

There is already such a unit in the game namely spearmen. They are cheap and to be honest quite useless on the field of battle. The only use I have for them is to garrison the cities.

Level 8 Human True Nerd
Alignment: Chaotic good
Location: Meran
Posted on November 28, 2010 at 10:26 pm

The idea is that the militia i think about cannot leave the town. Therefore the city stays protected even if you move all other units out of town. Because the AI doesn't leave anything behind when he moves its armies. Do you see my point?

Level 8 Human Perruptor
Alignment: Lawful
Posted on November 29, 2010 at 1:35 am

Also you have to over-garrison, so you'll have someone to send out to chase off light raiders, or to slip out and extinguish fires after they leave.

I think the problem is that you should get instant credit for any troops you put into the city, rather than having to wait a long time for the defense to increment up.

This would let you bring your whole army out for a stand-up battle, then run to the city if you lose, which I think was the common practice at that time.

Level 8 Human gamer
Alignment: True neutral
Posted on November 29, 2010 at 6:21 am

yup, the defensive bonus should build up from a fixed point, say 2 spearmen are present, so say this would be 300 per, starting from that 600 it will build up to fill the city's potential of say 1200 which drops at the same rate it goes up when you make a sally.

mimicking the extra baskets of missiles,rocks, barricades, etc etc... the defending garrison prepared when they were there.

a unit called militia could also be present at any one time formed from the entire free pool of men consisting of a lesser version of spearmen. they are unable to move from the city and will be permanently present. as I gather the recruitment pool represents the able bodied men ready for service they might aswell man the walls in time of need. Then again, a city with 0/150 in the pool with no garrison will have O defence and will surrender as soon as besieged so there should be a minimum size of this 'militia' consisting of the 'non-able bodied men' either too young or too old to bear arms the size of this minimum also corresponding with the maximum size of the pool, say 10%.

seen as this would cause some cities to have extraordinary defenses (pella=150+10%=165 militia+the garrison) this would make the city impervious to anything but a well organized siege. As it should be.

just take Athens for example. only by beating theyre forces in the field and by this depleting they're recruitment pool will a city of such magnitude fall in a short while. Just as the entire spartan army could do little but ravage the countryside whilst the Athenians refused to offer battle.

Level 17 Extraplanar gamer
Alignment: True neutral
Posted on November 29, 2010 at 4:30 pm

If any developers are reading this...

Yep, we're listening.

I've just been getting back to AI issues in the last week and I've got an endless list of things I want to improve. However, I'm always interested in hearing about particular concerns as it helps me decide what gets priority.

There are a large number of factors that can change how the AI responds to a situation which is why I put out the call for savegames so I could test the AI against a lot of "real" world situations. If you've got a savegame near the fight you're talking about I'd be interested in checking it out (anything can be sent to rob@longbowgames.com).

Regarding how city defenses are calculated: one of the reasons we made the change in defense gradual was to avoid problems/exploits when popping units quickly in and out of cities but I'll take a look at things again and see if there's room for adjustments. In the original Philip we made walls cost 2 pop which was meant to account for a minimal garrison that cannot be removed from the city. In Gold the effect of that minimal garrison still exists but no longer has a tie to population/recruits.

Level 8 Human Contractor
Alignment: Good
Location: Toronto
Posted on November 29, 2010 at 8:10 pm

The idea is that the militia i think about cannot leave the town. Therefore the city stays protected even if you move all other units out of town. Because the AI doesn't leave anything behind when he moves its armies. Do you see my point?

I see your point and it happens to me as well. But the opposite happens as well, namely that AI keeps all it's units in the city and losses all of them once the city is taken after I take it's defenses down with some ballistas.

When I am on the receiving end and I face the attacking enemy it all depends on the strength of his force. If it is a small raid and I have no troops to spare to face them in the open I just let them do their worst and take out as many as I can from the city walls. If the force is large enough that it might actually mount a successful siege I try and repel them within the city range if I am low on units.

Level 8 Human Perruptor
Alignment: Lawful
Posted on November 29, 2010 at 9:28 pm

If any developers are reading this...

Yep, we're listening.

I've just been getting back to AI issues in the last week and I've got an endless list of things I want to improve. However, I'm always interested in hearing about particular concerns as it helps me decide what gets priority.


A few more thoughts/facts about the original post. While the big sortie from Tricca to catch my Companions was IMO foolish, a big sortie when I was bringing my army up to Larissa caused me some grief, because lots of my stuff hadn't arrived yet. But ultimately they got beaten up pretty badly, and ended up having a low defense strength for Larissa for the reasons previously stated.

I think sorties can be good, but the AI (or human player) has to use some judgement on how much to leave in the city.

Letting a big army get trapped in a city doesn't usually work out well because they don't add to the defense, and once the city is invested they can't sortie out fast enough to do the necessary damage. (Note to players: apparently the gates on the cities aren't merely cosmetic; that's where troops actually enter and exit. So when you besiege a city with troops in it that could pose a threat, make sure you have line infantry right up against every gate, and missile troops in range of each gate, so you can turn any attempted sorties into a slaughter.)

Back to the AI. In the game I've been discussing I invaded Thessaly from the west. After I took Pharcadon I was deciding whether to attack Krannon or Larissa, and the AI kept moving a big army back and forth between them, apparently to whichever one I had the most troops near. (I don't know whether this was good or bad; I just offer it as an example of the AI in action.) It did leave a garrison in one city whenever it moved the army to the other, IIRC a couple of spearmen or peltasts. I do not remember what the cities' defense numbers were, but I think it let Larissa drop far below what it could have had.

Food is also an issue. The AI put fairly large armies into cities as I approached, with only 700-800 food in the city. So not only does a big army trapped in a city not help with the defense, it eats the food much faster than a basic garrison would. In the previously mentioned siege of Larissa the AI made a second sortie after the city was closely invested and they could no longer hurt me. I think it was triggered by running out of food, though I'm not 100% sure.

Finally, there doesn't seem to be much reason to leave troops in an unwalled city; they should either sortie or flee. The troops initially in Edomene just die in the city without putting up a fight, unless I venture too close with a weak unit before the rest of the army arrives. They do correctly sortie against a weak unit, but when I bring up something too powerful to sortie against successfully they just sit down and die.


There are a large number of factors that can change how the AI responds to a situation which is why I put out the call for savegames so I could test the AI against a lot of "real" world situations. If you've got a savegame near the fight you're talking about I'd be interested in checking it out (anything can be sent to rob@longbowgames.com).

I haven't been reading that thread because I didn't realize what it was about. I don't think I have anything relevant, but I'll look for situations when I have time to play some more.

FYI, I'm enjoying your game immensely.

Level 8 Human Perruptor
Alignment: Lawful
Posted on November 30, 2010 at 1:11 am

New one: playing Macedonia in the sandbox. First Autumn. Chalcidians massed troops at Krousis, then moved on Therme with apparent bad intentions, leaving 1x spearmen in Krousis. I had a couple of cavalry scout troops in the region, so I ran them around behind the invaders to burn crops. Their entire army is now rushing home, which is probably an overreaction. (Though they may not know how few troops I sent on the raid.)

More importantly for the current thread of discussion, when one of my cavalry approached Krousis, the remaining spearmen garrison came out to fight, which is probably right in general, but had the side effect of dropping the city's defense from 1600 to 400. And I do have a small army on the way with reciprocal bad intentions, so unless they can beat me in the field they will most likely lose Krousis.

In their position I would have kept the garrison in the city, and suffered the burned crops. With more foresight I would have left a second small unit in the city to go out and hassle any small raiding parties. (It doesn't take much... when the farm is close to town you just have to distract them from the burning and let the city's catapults hurt them until they decide to go home.)

Level 8 Human Perruptor
Alignment: Lawful
Posted on November 30, 2010 at 1:40 am

Now more of the same:

Bottike had 1x spearmen and 2x peltasts, but marched all three out against a single cavalry scout raiding their farms.

Olynthus had 1x spearmen and a second one building; they sent out the full strength unit, leaving only the building unit with current strength of 8.

Potidea had only 1x spearmen and a general, and sent the spearmen out against my raider near Olynthus, leaving the general behind. (He probably should have joined them if they thought best to go out.)

Amphipolis had only 2x peltasts and 1x Greek Cav, but they're sending everything out against a single raider. (However, a city that size retains a pretty decent defense for so early in the game.)

My small army is now behind Therme, so their main army is retreating back into Krousis, which will take a long time to build its strength back up.

My best suggestion at this point would be to set a dynamic "minimum garrison size" for each walled city, with value depending on the city's importance and its potential exposure to attack, and like the food transfers, never move a garrison unit out if that would cause a drop below the current target size.

I'll send you a save game.