Ai just attacks more frequently and with bigger armys. Also if you build walls it becomes really dumb and tries to find a way through before destroying your walls eventually.

Yep, they will adavance age faster, use bigger armies, attack more frequently, build forts and have a lesser handicap on resource gathering.
There is an interesting section on the wiki about it: https://ageofempires.fandom.com/wiki/Artificial_intelligence#Age_of_Empires_III

I also would like to add that, up until a certain previous patch that I don't remember when it came out, at least on Normal difficulty the enemy responded to attacks when his armies were intercepted by units or defenses, while now, inexplicably, he passes through them ignoring them. Even walls, before if they were in their path they tried to destroy them, while now they try to go around them without responding to attacks, unless after losing many units.

Originally posted by Zoltan Redbeard:

Yep, they will adavance age faster, use bigger armies, attack more frequently, build forts and have a lesser handicap on resource gathering.
There is an interesting section on the wiki about it: https://ageofempires.fandom.com/wiki/Artificial_intelligence#Age_of_Empires_III

I also would like to add that, up until a certain previous patch that I don't remember when it came out, at least on Normal difficulty the enemy responded to attacks when his armies were intercepted by units or defenses, while now, inexplicably, he passes through them ignoring them. Even walls, before if they were in their path they tried to destroy them, while now they try to go around them without responding to attacks, unless after losing many units.

This behavior is not unique to medium or easy difficulty levels, ive played against them on harder difficulties and while yes they do defend stronger and have faster economy, aswell as bigger armys, ive still seen them going around walls if i let a tiny bit open on purpose. Enough time for my towers to do a little damage before they reach my defense units.

Originally posted by Jadedragon:

Ai just attacks more frequently and with bigger armys. Also if you build walls it becomes really dumb and tries to find a way through before destroying your walls eventually.

does the AI "cheat" (e.g. get free resources) at certain difficulties?

Originally posted by Jadedragon:

[...]

This behavior is not unique to medium or easy difficulty levels, ive played against them on harder difficulties and while yes they do defend stronger and have faster economy, aswell as bigger armys, ive still seen them going around walls if i let a tiny bit open on purpose. Enough time for my towers to do a little damage before they reach my defense units.

Yes, it's really stupid and annoying, I really don't understand why they changed the previous to this behavior, the AI didn't act like this before.

Originally posted by JARSHAR:

[...]

does the AI "cheat" (e.g. get free resources) at certain difficulties?

As noted in the wiki I linked above, if not set manually, the AI ​​would appear to have a negative resource gathering speed bonus on all difficulties up to hard, where it is normal like the player, while on expert it should have a positive +50% gathering bonus rate.
There could be some inaccuracies because with the succession of patches and expansions it has not been constantly updated, but as a basis I tend to take it as good.

On terminology, I would also note that, when setting up a skirmish, it is called handicap, but this makes one think that a positive value has a negative effect, instead it should be read as a bonus, in fact the value set increases the player's overall gathering speed instead of decreasing it.

In conclusion, as of today the AI don't seem to have free resources per se, even if in the past the AI ​​had decks with more than 25 cards, but that's been fixed now.

Be warned that the jump between Moderate (which is really more like an Easyish-Normal) to Hard is noticeably steep--I've complained about this for over a year, but the fact remains that, while generally a good thing, the Hard difficulty has been updated over the years to have "human-like" strategy while Moderate has stagnated (and by the sound of previous replies, even gotten easier)...

all of this is to say, you can fight Moderates 1,000 times and not learn a single skill you need to defeat Hard.

You can "feel your way" around battling against 's Moderate, but you need to know how to play an RTS for real to stand a chance against Hard. See other forum topics for more details....

Originally posted by Zoltan Redbeard:

Yep, they will adavance age faster, use bigger armies, attack more frequently, build forts and have a lesser handicap on resource gathering.
There is an interesting section on the wiki about it: https://ageofempires.fandom.com/wiki/Artificial_intelligence#Age_of_Empires_III

I also would like to add that, up until a certain previous patch that I don't remember when it came out, at least on Normal difficulty the enemy responded to attacks when his armies were intercepted by units or defenses, while now, inexplicably, he passes through them ignoring them. Even walls, before if they were in their path they tried to destroy them, while now they try to go around them without responding to attacks, unless after losing many units.

Also during one of the last updates, the one good water map, Carib, was affected where the AI can no longer load artillery of any type on any transport. It can load troops but not artillery. So the transport sits on the shore making a continuous attempt but fails. Undeployed canon are perfect targets though it makes the game less enjoyable. My artillery can load into my transports though the process is slower. It has been reported previously. Until the focus is back on this game, I don't see any chance of fixing problems.

Originally posted by Elmer:

Until the focus is back on this game, I don't see any chance of fixing problems.

*Unless

Yes, you both are right, additionally, I do remember that once the AI also used to revolt from their Home City, spicing up and varying the matches a bit, but that behavior was patched out too (at least on lower difficulty levels), probably because it was done too often and they didn't get to balance the thing, because only one player can revolt per game (one per team after the DE I think) and the AI doing so, I think, prevented the player to revolt himself.

Originally posted by Zoltan Redbeard:

Yes, you both are right, additionally, I do remember that once the AI also used to revolt from their Home City, spicing up and varying the matches a bit, but that behavior was patched out too (at least on lower difficulty levels), probably because it was done too often and they didn't get to balance the thing, because only one player can revolt per game (one per team after the DE I think) and the AI doing so, I think, prevented the player to revolt himself.

Only one being able to revolt per match is a design desicion i dont understand at all. Why limit it to only 1 player in the first place lol.

Originally posted by Jadedragon:

Originally posted by Zoltan Redbeard:

[...]

Only one being able to revolt per match is a design desicion i dont understand at all. Why limit it to only 1 player in the first place lol.

It's a game decision that I don't understand either, later they changed it to one player per team, which is a little better, but I still don't see why everyone can't do it.
The only exception I think are the Mexicans, who I don't think thair revolts prevent the others from revolting, but in any case the arbitrary limit seems absurd to me too.

Originally posted by Zoltan Redbeard:

Originally posted by Jadedragon:

Only one being able to revolt per match is a design desicion i dont understand at all. Why limit it to only 1 player in the first place lol.

It's a game decision that I don't understand either, later they changed it to one player per team, which is a little better, but I still don't see why everyone can't do it.
The only exception I think are the Mexicans, who I don't think thair revolts prevent the others from revolting, but in any case the arbitrary limit seems absurd to me too.

I thought there would be some balance reason i could not see as im rather new-ish.
But welp, game devs will do game devs things XD Im used to weird decisions.

Originally posted by Zoltan Redbeard:

Originally posted by Jadedragon:

Only one being able to revolt per match is a design desicion i dont understand at all. Why limit it to only 1 player in the first place lol.

It's a game decision that I don't understand either, later they changed it to one player per team, which is a little better, but I still don't see why everyone can't do it....

Originally posted by Jadedragon:

I thought there would be some balance reason i could not see as im rather new-ish.
But welp, game devs will do game devs things XD Im used to weird decisions.

How long ago would this have been? I won a casual match as an entire team of Hungarians last year.

Originally posted by Primhose:

Originally posted by Zoltan Redbeard:

It's a game decision that I don't understand either, later they changed it to one player per team, which is a little better, but I still don't see why everyone can't do it....

Originally posted by Jadedragon:

I thought there would be some balance reason i could not see as im rather new-ish.
But welp, game devs will do game devs things XD Im used to weird decisions.

How long ago would this have been? I won a casual match as an entire team of Hungarians last year.

As far as I know, before the DE only one player for match could revolt, but this was changed when the DE was release allowing one player for team to revolt per match, this was also noted in the update 1529 released on October 20, 2020.
Since its release, AoEIII has tried to prevent the use of two identical civilizations in the same game, this would probably apply to revolutions as well so, perhaps, that was the initial motivation of the limit, even if there has always been a trick to get around this limitation for the main civilizations.

Anyway, I digged a bit into some of the changelogs that I've found, but I only get the following:

• "Fixed an issue where European civilizations would revolt too often." (Update 3552, October 22, 2020)
  
• "Improved how AI players utilize and employ Revolution features." (Update 5208, November 5, 2020)
  
• "Disabled the ability to Revolt (excluding South Africa) while a Treaty is still active." (Update 6159, November 12, 2020)
  
• "The AI can now only revolt if it has more than 60% of its allowed population, to prevent revolts that make very little sense." (Update 13.690, March 15, 2022)

This last one, even if it doesn't really convince me, may explain why on lower difficulty level the AI doesn't seem to revolt anymore, but I'm really not sure, because there were other changes on the AI behavior that weren't noted in the changelogs, like the ones we pointed out early in this thread.
Anyway, this is what I've found, but I don't rule out the possibility that I missed something, additionally, there are probably mods that allow all the players to revolt during a game.

Edit: I've also found:

• "Fixed an issue where AI armies would continue attacking walls despite having a hole through which to raid." (Update 9476, December 8, 2020)
  
• "AI-controlled players will now prioritize attacking crucial enemy structures on harder difficulty levels." (Update 9476, December 8, 2020)
  
• "Fix for AI players moving to the next building target before the current one is properly destroyed." (Update 43871, September 14, 2022)
  
• "Improved AI behaviour around walls blocking AI players' targets." (Update 47581, October 12, 2021)

Although it was not done in only one time and is not explicitly stated, these patch notes above may explain partially the behavior of AI armies that ignore both walls and who is attacking them as they move toward the enemy base.

Originally posted by Zoltan Redbeard:

Originally posted by Primhose:

How long ago would this have been? I won a casual match as an entire team of Hungarians last year.

As far as I know, before the DE only one player for match could revolt, but this was changed when the DE was release allowing one player for team to revolt per match, this was also noted in the update 1529 released on October 20, 2020.
Since its release, AoEIII has tried to prevent the use of two identical civilizations in the same game, this would probably apply to revolutions as well so, perhaps, that was the initial motivation of the limit, even if there has always been a trick to get around this limitation for the main civilizations.

Anyway, I digged a bit into some of the changelogs that I've found, but I only get the following:

• "Fixed an issue where European civilizations would revolt too often." (Update 3552, October 22, 2020)
  
• "Improved how AI players utilize and employ Revolution features." (Update 5208, November 5, 2020)
  
• "Disabled the ability to Revolt (excluding South Africa) while a Treaty is still active." (Update 6159, November 12, 2020)
  
• "The AI can now only revolt if it has more than 60% of its allowed population, to prevent revolts that make very little sense." (Update 13.690, March 15, 2022)

This last one, even if it doesn't really convince me, may explain why on lower difficulty level the AI doesn't seem to revolt anymore, but I'm really not sure, because there were other changes on the AI behavior that weren't noted in the changelogs, like the ones we pointed out early in this thread.
Anyway, this is what I've found, but I don't rule out the possibility that I missed something, additionally, there are probably mods that allow all the players to revolt during a game.

Edit: I've also found:

• "Fixed an issue where AI armies would continue attacking walls despite having a hole through which to raid." (Update 9476, December 8, 2020)
  
• "AI-controlled players will now prioritize attacking crucial enemy structures on harder difficulty levels." (Update 9476, December 8, 2020)
  
• "Fix for AI players moving to the next building target before the current one is properly destroyed." (Update 43871, September 14, 2022)
  
• "Improved AI behaviour around walls blocking AI players' targets." (Update 47581, October 12, 2021)

Although it was not done in only one time and is not explicitly stated, these patch notes above may explain partially the behavior of AI armies that ignore both walls and who is attacking them as they move toward the enemy base.

Wow thats alot of research you did there! Thank you! Its an interesting read and gives alot of insight. They try to make the AI smarter regarding walls, from what i can get from these logs, but AI found a diffrent way to be just as dumb XD

But tbf the AI in age of empires 3 has age on its back, its not like todays AI systems, red dead redemption 2 for example which is alredy a fiew years back but still holds as example to modern AI programming, they actively seek out advantage points and try to flank you during a shootout.

Im impressed how good the AI actually works for being in such an old game. Ive seen a newer game where AI does worse, but then again the focus is more on pvp anyway in the game im thinking of. So maybe not really a comparison.