Late-game AI unit clogging

[Thalassicus]

Recently I've been considering the issue of late-game air/land/sea unit balance on the Combat thread, and this particular topic is the problem of AI units clogging the map (like in infamous screenshots such as this). It's a problem in both vanilla and this mod and not easily solved. If the human player has X units, the AI has to build more because it's simply not as good managing each unit... so it favors quantity over quality. This runs into problems with the 1 unit per tile restriction though.

In Civ 5, air offers a potential solution for the late game and might actually be very effective for AIs. It's not obvious because their flavor values don't favor air in vanilla so they don't build any, and we're used to a Civ 4 mindset where everything could stack. In Civ 5 however, air units have this unique advantage... since after all, in real life aircraft can literally stack at different altitudes!


In some test games I shifted AI priority in the very late game towards missiles, which have some notable characteristics:

• No stacking restriction
• No pathfinding or battle line issues
• No worry about experience
• Spammable due to no resource requirement

Units with some or many of these characteristics are perfect for an AI that has to rely on quantity over quality, because the AI doesn't assess threats well and calculating 1upt unit placement efficiently is infeasible for a computer (it's an np problem). I've found in my test games that shifting things slightly towards missiles reduces the unit clog issue in the late modern and future eras. The AIs use these extra units as filler to make up for the skill gap between themselves and human players.

The industrial / early modern AI needs a spammable filler unit too, though. My first thought was an industrial era missile like the V2 Rocket. The downside is it'd add another unit to an already cluttered era, and I don't entirely like units that are 100% expendable (unless it's sufficiently powerful like nukes) since it results in somewhat tedious micro.

To adapt the vanilla game to achieve the goal of a filler unit without adding a new unit, I realized bombers fit the first two traits in the list but not the last one (and ignoring the third trait because it's not as important for the topic of unit clogging). Removing the resource requirement entirely would probably too much, so I figured why not reduce it? It has obvious UI issues (0.8 of a resource has no meaning) so I came up with an alternative. If units used to cost 1 oil and deposits give 1 oil, scale them up so units cost X oil and deposits give X, where X might be any number like 2 or 10. This allows more flexibility in resource requirements. Uranium does this, where nuclear missiles cost 2 of the resource. This is basically like my thought about scaling yields in the Double down? thread. To put it simply, if units consume X more resources but deposits also give X more, it scales everything up without changing the math (2/1 = 4/2) but allows for more room to adjust things.

Allowing players build a larger air force seems like a possibility that would mostly fit within the existing structure of the game. If we can figure out a way to solve this problem without making bombers fit the role and without adding a new unit to the game to do so, I'm all ears.

Anyone have some thoughts on the matter?

 

[Dunkah]

Human players building lots of AA may skew this a bit.

Sounds like a way to make trading SR's viable again as well. As there will actually be extra in the game and every 1 equals 2 to the AI.

 

[Ahriman]

My comment on the "infamous screenshot":

Which was made in pre-patch vanilla.
The problem with that screenshot is that the AI should have attacked him long ago and rolled over him with an endless swarm.
The screenshot demonstrated a failure of the AI to launch intercontinental invasions. Its a bit better at that now.

I haven't observed serious late-game AI clogging, and I think that if the AI has enough units, it should go use them and kick someone's teeth in.

So, this is a diplomacy/aggressiveness issue, to me. I don't see any need for other changes, and I think messing around with units requiring more than 1 strategic resource is unnecessary confusion.

 

[Maxii]

Thal, I like your idea of more emphasis on air for the AI. It makes them more unpredictable and effective in combat and does reduce the unit clutter which itself makes the AI more effective.

Combining this with the battleship debate, consider this - eliminate the battleship entirely. I find destroyers already largely accomplish what the battleship is intended for. We don't need 2 modern surface ship types with a ranged fire mission.

Instead, make carriers the strategic resource user and make them REALLY tough, like they are in real life. Think of them as a battle group. All the rest of the units in a battle group are there to support/defend the carrier. By tough, I mean it could take 10-15 attacks from a destroyer or air unit to sink a carrier. By making them that tough, it deemphasizes the need for the AI to protect the carrier, something it doesn't really know how to do. I'd also put a cap (another debate - hard or soft...) on the number of carriers an empire can deploy so the AI doesn't spam them to the exclusion of other items.

This reinforces the air emphasis for the AI.

 

[Thalassicus]

It's true that unit clogging doesn't reach the level of that screenshot, though I don't think it's due to overall AI passiveness. I see it in each game where I get to the modern era... not everywhere on the map, but in at least one spot. In test games where I work on modern AI unit balance things typically look like the image below wherever there's a war going on.

Songhai and Siam on the left and right are at war with Mongolia in the center. The greater emphasis on air helped them a lot... there's about 23 aircraft in this image, and if those were ground units we'd see serious clogging issues. Overall I'm rather happy with their unit balance now, though they're still building slightly too much AA (something I'm tweaking). They build a great combination of infantry, artillery, AA and air. The problem is although the emphasis on air significantly reduces clogging, they can't build many tanks. It's not entirely a bad thing (AI isn't very good at managing fast units like tanks) but still something on my mind.

 

[Tomice]

I haven't followed the discussions for a few days, but what about using aluminium for all air units, even the industrial ones? You could balance air and land/sea units seperately this way.

 

[Thalassicus]

I did get a suggestion to that effect in email recently in fact... something I'm thinking about at least experimenting with for the next beta testing cycle.

Heyo, long time no talk.

Two things, one a suggestion and two a query that probably gets me nowhere.

1. Aluminum and Oil are obviously a total mess in vanilla. You set up one solution, but I came up with another if you aren't satisfied with it. That is I made Aluminum and Oil more like Iron and Horses - they work on entirely different classes of units.

Aluminum:
Fighter/Jet Fighter
Bomber/Stealth Bomber
Helicopter
Submarine/Nuclear Submarine

Oil:
Tank/Modern Armor
Battleship/Missile Cruiser
Carrier
Rocket Artillery

The idea is that you can field a pretty weak army with neither of these resources but you can field a reasonable army with one and a complete combined arms army with both. It also means that neither goes obsolete, upgrades make sense, and you can even change the techs that obsolete units so the modern unit build screen doesn't have literally 30 units on it - Fighters/Tanks/Submarines/Battleships/Bombers all go obsolete.

I also love the idea of having strategic resources work on both economies and armies so I am trying to work Oil/Aluminum into buildings - Oil required for Laboratories and Aluminum for Broadcast Towers at the moment, but that might change.

 

[Tomice]

That's exactly what I meant At least the first part about SR's.

 

[Ahriman]

Well, I haven't encountered such unit clustering as to be problematic, but similarly, I haven't played a whole lot of late-game in this mod yet.
But I still think that tanks are also relatively effective in AI hands even if they have a huge army. Their high movement rate means they can charge out ahead and attack an enemy unit, so its pretty easy for them to get where they need to go in order to kill stuff.

I'd oppose the idea of taking oil requirements away from aircraft or adding aluminium requirements.

The whole point is to encourage strategic tradeoffs. You can have lots of tanks *or* lots of aircraft *or* some of each, but not lots of both. You'll probably favor aircraft more on a land-based map, and battleships more on a more naval map.

And the whole point is to make the specific resources feel really important. There just isn't enough room in the late eras to have 3 important late-game resources (oil, aluminium, uranium).

I also don't like the proposal of making basically every modern unit into a strategic resource unit. I think the strategic resource units should be "special" and powerful and superior.
In the proposal from the email, you're going to see late-game armies of nothing but mech-inf and mobile SAMs, because everything else is a resource requirement.
No-one will ever build a carrier, or a submarine, and probably no helicopters, because those detract from more generally useful units.

I would definitely consider though making the missile cruiser a *real* advanced battleship (and an upgrade from it that was at least as good in every stat including range and ranged attack ) that retained an oil requirement.

Basically though: I'd prefer to keep the resource requirements just for specialist superior units, and then use balance tweaks to make sure that those units really are superior.

 

[Thalassicus]

I would definitely consider though making the missile cruiser a *real* advanced battleship (and an upgrade from it that was at least as good in every stat including range and ranged attack ) that retained an oil requirement.

I entirely agree about this point in particular, and did so in one of the most recent beta versions.

 

[Ahriman]

Man, I need to stfu until I've done more lategame testing, so many suggestions are things you've already done.

 

[SSgtDuke]

I haven't had any significant problems with AI clogging up the map (except maybe the poor CSs and their small amount of land). It's definitely more crowded in the late eras, but this seems quite natural. If I'm at war with a civ then I'm fighting through their units. If we're at peace then we're generally not crossing borders and don't get in each other's way.

As far as the general balance between land, air, and sea is concerned, I think it's just about right the way it is now. It would be nice to see the AI build a few air units to balance out their militaries, but I don't want to be able to build more air units and I don't want them building more than a handful either. When I have more than 5 or 6 air units it can take quite awhile just to use all the moves per turn. In the one game when an AI civ was regularly using 5 or 6 air units it also took quite awhile just waiting for the turns to finish. I'm afraid increasing the number of air units available to each civ (and an AI that is actually using air units) would make the turn times unbearable and would be an annoyance to manage all of them.

The AI building a bunch of missiles (in a balanced way) sounds good though. It definitely puts some fear in me when I see cities with 3 missiles waiting for me. A strong civ already seems to do this quite well. Though on a side note, why can I see city air units behind the FoW? It seems like a bit of a cheat, but I guess it does work to possibly scare away would-be attackers.

The idea of scaling up oil resources and having some units use more (or less) than one oil really turns me off. Nuclear missiles requiring two uranium doesn't bother me because it's the only item in the game set up like that and it's such a super-mega weapon. Normal units requiring various amounts of resources doesn't feel right to me. I don't see any overly significant unit/type balance issues and this change seems quite complex, confusing, and unnecessary.

 

[Ahriman]

I basically agree with Duke on everything here.

More missiles via-flavor tweaks is something that can help the AI take advantage of massive production without actually changing the game rules that affect the human player.

Changing game rules that *does* affect the human player (eg by making aircraft not require much oil) is less good as an approach.

 

[Thalassicus]

Do you feel the V2 Rocket approach would be a better solution, then? I'm open to either one, though obviously the rocket would mostly be an AI thing (tedious micro for expendable units). This is one of those situations where if there really isn't a better unit/building to deal with an issue, I'm open to adding a new one.

 

[SSgtDuke]

Just to make sure I'm clear, the full issue is that the AI has too many land units clogging the tiles and doesn't defend itself well? The former hasn't been an issue for me, especially that early, though I do tend to roll over civs in the industrial/early modern era and so the AI could probably use some help. But I fear that if they spend too much resources on new rocket units that they would be even less capable of mounting an offence.

You're thinking to basically copy the guided missile, give it a new name, and reduce the strength?

 

[Thalassicus]

Right, basically give them a way to expend extra production in the industrial / early modern period on a unit that won't possibly run into any 1upt issues, whether that's a bomber, missile, or some other form of air unit. This is primarily a problem on immortal and deity difficulties where they build units 60%-100% faster than the player.

It'd be a copy of the guided missile with lower strength, cost, etc. I actually gave the guided missile the same Demolish "+100% vs Cities" promotion as siege and naval units when I added that promotion to the game, so it's decent on offensives (90% of games probably never get to that point though).

 

[SSgtDuke]

This is primarily a problem on immortal and deity difficulties where they build units 60%-100% faster than the player.

That could explain why I haven't really been seeing the clogging problem. I only play on Emperor, which I guess keeps them from going so wild. In my next game I'll try to imagine the effect of a rocket becoming available sometime around Combustion (I would guess) and give some feedback after that.

 

[Thalassicus]

Combustion would make sense as it leads from dynamite/artillery, and most early rockets were used as a form of artillery (though the Combustion one technically refers to internal combustion engines it's about the same era). Combustion and Flight represent c.1940 era technology, while the "Rocketry" tech seems to portray the space flight, helicopters, and missile systems of c.1970.

 

[Ahriman]

Do you feel the V2 Rocket approach would be a better solution, then?

Probably, though I'd worry that it might be really "not fun" for the player. There's nothing you can do to stop a missile attack, and no amount of clever unit placement will help you.
It might be really not-fun if the AI can just literally turn their production advantage into destruction of your carefully shepherded super-veteran units.

But I need more late game playtest experience first.

This is primarily a problem on immortal and deity difficulties where they build units 60%-100% faster than the player.

I'm also not sure that we should really start changing core mechanics to counteract a problem which only happens on Immortal and Deity.

 

[Thalassicus]

The first solution I looked for was actually something to tell them a "maximum percentage of land tiles to cover with units," but didn't spot anything. I'm not sure a hard cap would have been the way to go anyway, since if they hit that and capped out their resource usage for air they'd have no military units to build.

One thing to consider is on other difficulty settings AIs still try and build the same number of units, just do so more slowly. Given enough time and a slow enough pace to the war they get to the same level of clogging (such as if there's a lot of rough terrain). I've seen it a few times on emperor difficulty. It depends on what's considered as a core mechanic... I play on immortal so it's a core mechanic for me.

I agree aircraft aren't an ideal solution, but they do reliably work to solve the issue. In a way aircraft are actually easier to counter than artillery - there's nothing we can do about a ranged unit stationed in a city bombarding our army each turn (until the city is captured), while a rocket attacking each turn can be intercepted. Fighters and AA are good counters to air, and it'd give us a reason to actually build them. I've had very little reason to ever build anti-air units.