[R&F] Upgrading units

[acluewithout]

A random thought I’ve been mulling over. Should players be able to upgrade units at all?

I feel like upgrading units, combined with there being no real limit to how many units you can have, cause just a tonne of balance problems.

Indeed, it seems really odd to me that there is no limit on how many units you can have. The way the game is now you’re sort of incentivised to keep building units (at least in the early game). Early units give you a lot of bang for your buck, and even more so once you factor in experience and upgrades. If I’m not warmongering, I still tend to build quite a few ancient era units and then they just sit around and then get suddenly upgraded when I get attacked or someone attacks me (hey presto).

Looking it another way, there never seems to be a reason to disband units. It make sense to keep ancient era units around forever, because they provide low cost fog busting and or garrison unit bonuses, and always be instantly upgraded if suddenly war.

I think the game would be more interesting if upgrading was harder. Perhaps you could have some sort of “force limit” giving a soft cap to how many units you can have. It would increase maybe with governments , policies and or military infrastructure. Going over your force limit would massively increase maintenance and production costs for units and maybe also create amenity issues. The big catch would be that more advanced units would eat up more of your force limit, so upgrading all your old units wouldn’t be an option any more - indeed, you’d have to disband some units to make room for upgrading others.

Having more restricted numbers of units - and making overall harder to keep rolling over your army into more and more advanced units - would not just make the AI more competitive but would maybe make loyalty and city flipping a much bigger deal. Because you couldn’t just override loyalty by steamrolling a tonne of cities all at once, and your own cities flipping which create much bigger drains on your (limited) military.

 

[Boris Gudenuf]

Right now, there is only a 'soft' limit on units, in that they have increasing Maintenance Costs as the game progresses. It's a very soft limit, though, since there are Social Policies to reduce the Maintenance Costs and doing virtually anything with Trade Routes and Commercial Hubs will bring in enough Gold per turn to cover a lot of units, normally.

Civ V had a 'Force Limit' which if you exceeded dropped your production for every single unit you were over the limit. I liked that, because it represented very neatly the fact that too many men standing around waving spears were not men that were growing crops or hammering iron into spearpoints. I would love to see something like that implemented for Civ VI: a limit on number of military units, perhaps with each Scout/Recon unit counting as 1/2 unit (smaller numbers of men in scot/special forces than in, say, an Infantry Host) and the total limit being based on your total population. Exceed the limit, and your Production would drop by X % for each unit you exceeded - going over the limit by any great number would, basically, have sucked everybody into the army and leave no one at home to build/manufacture anything.

This would add some interesting twists to the current strategies in the game:
Getting your cities to grow faster would be really important to getting a bigger army - and the Policies and Era Effects that grow citi4es faster or start cities with 3 population instead of 1 would get very, very important.

Losing cities could result in a 'snowball' effect where you start running out of Force Limit to property defend the remaining cities, production of new units drops, and your Civ goes Down The Tubes in a hurry.

You could also include some interesting historical things in the game with this kind of Limit. Add real Mercenaries - troops you can 'hire' from a City State or even another Civ, and they do not count against your Force Limit because they aren't coming out of your population.

 

[Boyan_Sun]

Another problem with upgrading units is the exchange rate from gold to production.

• In Civ4, yield rate of gold and production is nearly 1:1, hurry production with gold is 4:1(exchange rate 25%), upgrading rate is 3:1(exchange rate 33%). So it is very uneconomic to upgrade units.
• In Civ5, yield rate of gold and production is 1:1 ~ 2:1, purchase units rate is 3:1 ~ 5:1(exchange rate 20%~66%), but upgrading rate is 2:1(exchange rate 50%~100%). Therefore, it is most economical to keep the ancient units upgraded all the time, even promotions will be retained, leading to invincible talent. This led to a strange rhythm in the game, where everyone build a few archers from ancient age, all the way upgrading to the information age, rarely or never train new units.
• In Civ6, designers learn from civilization 5's failure. They set yield rate of gold and production is 2:1, purchase units rate is 4:1(exchange rate 50%). After that, they set the upgrade rate to 1.5:1(exchange rate 133.3%)... WTH? And that's not all, they think that is still too low, so they add a card called "professional army", then the upgrade rate becomes 0.75:1(exchange rate 266.7%)...Well, maybe only idiot will train new advanced units(Yes, that's what the AI does, that's why AI is so weak). Well, do you think this is the end? No! The designers finally realized the problem and added remedial measures to the R&F expansion - now we can always build earlier units if you only have 1 strategy resources, so we can always upgrade to get that 266.7% much easier... (Of course, AI still won't do this, makes them weaker)

I have always felt that a good game design should give players a variety of choices, and the value difference between these choices is not too large, so that different tactics can be developed. However, the various designs of civilization 6 obviously have one option that is far superior to other options, so there is only one option to play well, which is very disappointing.

 

[Arent11]

military infrastructure. Going over your force limit would massively increase maintenance and production costs for units

This. Simply make encampments, barracks, castles etc. give you "support" like in master of orion 2. "Support" allows you to maintain units for free & if you go over the limit, you have to pay lots of money.

Regarding the upgrade problem it is very simple: Make upgrades so expensive that it only makes sense to upgrade seasoned units. In this way everyone will have a little veteran force from ancient times, but most units will be fresh recruits.

 

[Disgustipated]

Also want to add that higher level encampment buildings should give promotions to make hard building units later in the game more attractive. Say 1 promotion for armory and another (for a total of 2) promotion for military academy.

 

[acluewithout]

I like the sound of how Civ V did it.

I like the idea of being able to upgrade units. I do sometimes get attached to some units - so it’s fun keeping units around.

I think part of the problem is that, deep down, Civ VI isn’t big on making you manage your empire. “More” is basically always “good”, albeit the game sometimes gives things diminishing returns (so, more science via a research lab is still “good” but maybe doesn’t give as good a return for your hammers as you got from universities). Military follows the same philosophy - there’s no real requirement to manage your military (beyond maintenance, which is laughable). So, more army is always good, and the earlier the better (particularly given rising production costs).

I think what I’d like to see is not just a “cap” on units. A soft or hard cap would help, but you’d end up just building whatever it is you need to increase that cap, so you’d end up in the same place just with extra step.

Instead, I’d like to see your “force limit” working like housing, driving down production or gold if you go over it, perhaps making you use precious card slots to boost it. But more than that, Is like to see the absolute size of your military (regardless of your force limit) having some sort of negative impact on your empire. So, the more you militarise, the harder it is to develop other parts of your economy.

 

[AmazonQueen]

I like the sound of how Civ V did it.

I like the idea of being able to upgrade units. I do sometimes get attached to some units - so it’s fun keeping units around.

I think part of the problem is that, deep down, Civ VI isn’t big on making you manage your empire. “More” is basically always “good”, albeit the game sometimes gives things diminishing returns (so, more science via a research lab is still “good” but maybe doesn’t give as good a return for your hammers as you got from universities). Military follows the same philosophy - there’s no real requirement to manage your military (beyond maintenance, which is laughable). So, more army is always good, and the earlier the better (particularly given rising production costs).

I think what I’d like to see is not just a “cap” on units. A soft or hard cap would help, but you’d end up just building whatever it is you need to increase that cap, so you’d end up in the same place just with extra step.

Instead, I’d like to see your “force limit” working like housing, driving down production or gold if you go over it, perhaps making you use precious card slots to boost it. But more than that, Is like to see the absolute size of your military (regardless of your force limit) having some sort of negative impact on your empire. So, the more you militarise, the harder it is to develop other parts of your economy.

In Civ II (maybe Civ I as well, can't remember that far back) units cost shields for their home city, reducing production.
Maybe something like give a base support limit based on total pop of cities, modify it by government type, encampments and their buildings.
Up to that limit have units cost maintenance same as now, increase it when they are outside your borders. Scouts and civilian units never cost maintenance or count towards your force limit.
Above that limit you start getting production and growth penalties.

Would also make the unique and late game versions of scouts more valuable but I can't see that as a problem.

 

[UWHabs]

I think units should be cheaper to build, but more expensive to upgrade. I think it would make sense if the only units that you actually upgraded were ones that had accumulated promotions. Basically, if you want to keep your veteran units, be ready to pay (a little) for that privilege. Of course, that would change a lot, as it would probably kill the current knight rush, for example, as you can't pre-build the earlier era units and upgrade en masse without paying a ton.

 

[criZp]

Number of units are limited already by gold per turn. Upgrading units is kind of necessary because building stuff only to have to delete it not too long after isn't fun.

 

[Cedbird77]

Right now, there is only a 'soft' limit on units, in that they have increasing Maintenance Costs as the game progresses. It's a very soft limit, though, since there are Social Policies to reduce the Maintenance Costs and doing virtually anything with Trade Routes and Commercial Hubs will bring in enough Gold per turn to cover a lot of units, normally.

Civ V had a 'Force Limit' which if you exceeded dropped your production for every single unit you were over the limit. I liked that, because it represented very neatly the fact that too many men standing around waving spears were not men that were growing crops or hammering iron into spearpoints. I would love to see something like that implemented for Civ VI: a limit on number of military units, perhaps with each Scout/Recon unit counting as 1/2 unit (smaller numbers of men in scot/special forces than in, say, an Infantry Host) and the total limit being based on your total population. Exceed the limit, and your Production would drop by X % for each unit you exceeded - going over the limit by any great number would, basically, have sucked everybody into the army and leave no one at home to build/manufacture anything.

This would add some interesting twists to the current strategies in the game:
Getting your cities to grow faster would be really important to getting a bigger army - and the Policies and Era Effects that grow citi4es faster or start cities with 3 population instead of 1 would get very, very important.

Losing cities could result in a 'snowball' effect where you start running out of Force Limit to property defend the remaining cities, production of new units drops, and your Civ goes Down The Tubes in a hurry.

You could also include some interesting historical things in the game with this kind of Limit. Add real Mercenaries - troops you can 'hire' from a City State or even another Civ, and they do not count against your Force Limit because they aren't coming out of your population.

A force limit would be cool if the limit was tied to your population. For instance. You can raise 10,000 troops every 2 million population. As your civics etc advance that number is raised . Or certain Civs / leaders have lower force limits.

But if your at war. That force limit should be stretched....

 

[MooFreaky]

This. Simply make encampments, barracks, castles etc. give you "support" like in master of orion 2. "Support" allows you to maintain units for free & if you go over the limit, you have to pay lots of money...

A force limit would be cool if the limit was tied to your population. For instance. You can raise 10,000 troops every 2 million population...

A combination of these 2 suggestions would be good. The idea that you have a cap on units, so you actually need to invest in the key factors for making war. ie Military encampments and population to field an army.
It would actually encourage 2 other factors of the game that are currently less important, growing your cities and building encampments, both of which are currently less important than pumping out units. And because of one unit per tile, I wouldn't mind seeing other limits. Such as, if you build too many units in a city you lose population points. If you are sending that many of your men off to fight then you are going to drop your productivity at some point.

All these things also track historically, being seen over and over again.

 

[Archon_Wing]

Civ 6's unit upgrade system is the worst of both worlds. In Civ 4, units were able to be upgraded to multiple types of units and it cost a good amount but not enough to be prohibitive. In Civ 6, unit costs escalate too fast by era, thus making hard building units too ineffective. Thus I think it should be less convenient and cheap to upgrade units.

I think I'd suggest the following.

-- Increase the cost of upgrading by 25%, and free promotion removed.
-- Professional Army no longer reduces upgrade costs. Instead, it gives upgraded units an extra promotion.
-- Upgrade costs are reduced by 25% in a city if....
The city contains an encampment or if it's a military CS you are suzerain of. (Does not stack). If the city has an armory or the war department, upgrade costs are reduced by 50%. (Does not stack with anything)
-- Medieval units cost 10% less, Renaissance and later units, as well as all t3 buildings cost 20% less and cost 1 less maintenance.
-- Units may not be upgraded in an occupied city.

 

[acluewithout]

I agree the cost of upgrading units needs to be massively rethought.

I think having them cheaper to upgrade in encampments etc. would maybe be pain - you’d end up just marching units backwards and forwards to upgrade them. It’s bad enough doing that with natural wonders that give unit bonuses.

I think they should just get rid of the professional army card. Upgrading should just cost a chunk of change and that’s the end of it. Instead, I’d prefer if you had to actually slot a policy card before you could even upgrade. So, having the tech alone is not enough - you need to unlock a policy card and slot it to even have the ability to upgrade.

If the game had a force limit, I’d like to see it tied to more than just pop. Maybe pop gives you a base force limit, and then it increases with certain buildings (eg factories, military academies). There should also be policy cards, so you can force an increase to your force limit but it costs you a policy slot. Approaching and exceeding your force limit should also create happiness issues or other issues (including maybe diplomatic). Likewise, maybe being near your force limit could improve loyalty subtly.

 

[Boris Gudenuf]

I agree the cost of upgrading units needs to be massively rethought.

I think having them cheaper to upgrade in encampments etc. would maybe be pain - you’d end up just marching units backwards and forwards to upgrade them. It’s bad enough doing that with natural wonders that give unit bonuses.

I think they should just get rid of the professional army card. Upgrading should just cost a chunk of change and that’s the end of it. Instead, I’d prefer if you had to actually slot a policy card before you could even upgrade. So, having the tech alone is not enough - you need to unlock a policy card and slot it to even have the ability to upgrade.

A "Professional Army' realistically, gives you a cadre of men who soldier all the time, so they have more time to train with new weapons and equipment. On the other hand, 'professional armies' are notoriously resistant to change unless it is forced upon them. The most common 'forcing mechanism' is to get beaten in a war, which forces you to rethink how you were doing things. This is not practical in Game Terms, since it is pretty obvious how that could be 'gamed'. Having a large infrastructure, though - encampments, barracks, stables, armories, et al, is an obvious sign of a large professional army, so the 'ease of upgrading' could simply be tied to the percentage of cities that have such infrastructure - that way, a Civ with 3 cities that all have encampments, for instance, can Upgrade its forces much faster and cheaper than an Empire of 20 cities only 5 of which have encampments.

The expense of Upgrading, I think, should be more tied to the actual expense. For instance, any naval Upgrade basically means you are building an entire new ship (it is Not Possible to 'convert' a Quadirime hull into a Frigate hull no matter how clever your shipwrights are) - so the only cost savings over a new build is that you have experienced crews - which still have to be retrained on the new ships. Naval and aircraft Upgrades should, therefore, be almost as expensive as new builds. Land unit Upgrades are more flexible: spears to pikes is cheap, both in equipment and retraining. Swords to muskets is more expensive, but not that much more: muskets were actually cheaper in metallurgical expertise than good plate/mail armor or fine steel swords, and musket men could be trained in a few weeks or months. Cavalry to Tanks, on the other hand, would be Very Expensive: major industrial costs for the machinery, and major retraining costs for the crews, and major reluctance on the part of cavalrymen to give up their horses (in every army: I could cite specific examples from the pre-World War II US Army, British Army, French Army, Soviet Army, and German Army - it's a universal Cavalry Thing).

By 'juggling' the Upgrade costs according to Actual Costs and relating Upgrades to Infrastructure on hand for retraining (encampments, etc) I think we could come up with a much better system than the 'one set of costs fits all' approach that we have now.

If the game had a force limit, I’d like to see it tied to more than just pop. Maybe pop gives you a base force limit, and then it increases with certain buildings (eg factories, military academies). There should also be policy cards, so you can force an increase to your force limit but it costs you a policy slot. Approaching and exceeding your force limit should also create happiness issues or other issues (including maybe diplomatic). Likewise, maybe being near your force limit could improve loyalty subtly.

The basic 'cost' would be Total Population, if for no other reason than it is an easy Base Figure to count - number of population points per city times number of cities, no variation.

But you are exactly right that there are a number of 'modifiers' to that basic Unit Limit. The first could be tied to Government Type: ancient to pre-modern governments simply could not 'mobilize' as great a percentage of their population as Industrial Era and later governments/societies can and do, so the Unit Limit could be modified by Government Type - or simply by the number of Policy Slots in the government, which is already in the game and makes a modifier already linked linked to the Eras.

There are also possible Policy Cards that could modify the Limit. Already in the Game are:
Conscription, Levee en Masse, Defense of the Motherland, Press Gangs, Patriotic War, Total War, all of which historically were related to mobilizing a higher percentage of the population. Even Propaganda could be used to make it easier to enlist parts of the population, and change the Unit Limit.

There are Declaration of War types that could conceivably allow you to mobilize more of the Population Points: historically, Wars of Religion or Ideology energized more of the population to battle than simple wars of Conquest or for Gain.

 

[Archon_Wing]

think having them cheaper to upgrade in encampments etc. would maybe be pain - you’d end up just marching units backwards and forwards to upgrade them. It’s bad enough doing that with natural wonders that give unit bonuses.

That's the point. This would make encampments more strategically important, and also get rid of the "upgrade while rolling through people's cities at zero disadvantage" mechanic that happens now. The overwhelming convenience of buy/upgrade makes hard building not only underpowered but actually a negative. Being penalized because you didn't spam tons of ancient units is just dumb from any perspective especially when doing so was already so beneficial.

War in Civ 6 lacks strategy and this is not just because the AI is poor. Combat is based off of immediate tactics (target weak units, use rivers and hills) but there isn't much involving a bigger scheme. Incidentally, this is why I chuckle at people thinking 1upt requires more strategy, when it's clearly more of a tactical mechanic. Which is fine, of course, but I think there should be more to war than that.

In the end, we should shy away from just thinking about nerfing/buffing something but rather consider what something brings to the table. For example, in single player, you could double encampment fortification strength and yet people still won't build them because they don't really provide the things players need. Power creep can also be a bad thing, and while R&F was relatively restrained in this manner, there has been some that has rendered a few things redundant, such as that CS's ability to buy walls with faith.

Though certainly, I think some items such as upgrading are probably objectively too strong no matter how you spin it.

I think they should just get rid of the professional army card. Upgrading should just cost a chunk of change and that’s the end of it. Instead, I’d prefer if you had to actually slot a policy card before you could even upgrade. So, having the tech alone is not enough - you need to unlock a policy card and slot it to even have the ability to upgrade.

I actually think that is too complicated. I think it's better to have mechanics stay consistent and have cards enhance whatever you're doing for the sake of min-maxing but options should always stay available. Getting rid of the card is also fine by me, but I think it'd just be interesting to have something interact with that mechanic. Locking a feature behind a card actually makes it even more important.

For example, under my suggestion, you may not actually need to understand the mechanics fully to still be able to upgrade even if you pay some extra gold, but you could do better after learning about it all.

 

[kaspergm]

I'll go a little bit against the tide here and say that I don't think units are too cheap to upgrade, at least not universally. One case I think is really painful is the 190 gold to upgrade an Archer to a Crossbowman. That really hurts if you are doing it in numbers.

BUT the Professional Army policy card is so incredibly broken. I'm not even sure there's any good way of fixing it other than nerfing it into oblivion. I think the problem is inherent with the policy system, the fact that you can swap-in-swap-out cards every other turn at will and reap the full benefit obviously opens up loopholes like this. There are others, like the reduced cost to buy tiles, but that one only offers 20 % discount, just to give a frame of reference, so that would probably be the level one should aim for to balance it out without any major overhauls to the card system.

Another opportunity would be to link the upgrade cost to the unit building cards instead. So rather than having one card that offers a discount on upgrading all units, there is one card that offers discount on building AND upgrading melee units, one for mounted units, one for naval units, etc. That would make it less easy to abuse. Ideally there should be some sort of penalty for changing cards in and out too often, for instance when you change in a card, you need to wait 10 turns or whatever before you can swap that card out again, or at least doing it will carry some sort of penalty (gold and/or other).

On top of this, I agree unit production cost from medieval and onwards needs to be cut. I've said it before, but I feel production costs (units, buildings, districts) are balanced around the original stackable industrial zones, and they never tweaked anything after that feature was removed. So basically that means everything in late game costs too much.

 

[UWHabs]

I'll go a little bit against the tide here and say that I don't think units are too cheap to upgrade, at least not universally. One case I think is really painful is the 190 gold to upgrade an Archer to a Crossbowman. That really hurts if you are doing it in numbers.

BUT the Professional Army policy card is so incredibly broken. I'm not even sure there's any good way of fixing it other than nerfing it into oblivion. I think the problem is inherent with the policy system, the fact that you can swap-in-swap-out cards every other turn at will and reap the full benefit obviously opens up loopholes like this. There are others, like the reduced cost to buy tiles, but that one only offers 20 % discount, just to give a frame of reference, so that would probably be the level one should aim for to balance it out without any major overhauls to the card system.

Another opportunity would be to link the upgrade cost to the unit building cards instead. So rather than having one card that offers a discount on upgrading all units, there is one card that offers discount on building AND upgrading melee units, one for mounted units, one for naval units, etc. That would make it less easy to abuse. Ideally there should be some sort of penalty for changing cards in and out too often, for instance when you change in a card, you need to wait 10 turns or whatever before you can swap that card out again, or at least doing it will carry some sort of penalty (gold and/or other).

On top of this, I agree unit production cost from medieval and onwards needs to be cut. I've said it before, but I feel production costs (units, buildings, districts) are balanced around the original stackable industrial zones, and they never tweaked anything after that feature was removed. So basically that means everything in late game costs too much.

Yeah, I agree with most of this. Upgrading is too cheap relative to building, but whether you fix that by reducing building costs, or increasing upgrade costs, both valid.

i do think Professional Army would drop a lot in value if it changed to being a 25% reduction. That would be enough that you want to swap it in, but not so OP that you feel guilty doing any upgrade without it. And while it would be interesting to have different cards affecting upgrade costs for each class of unit, I wonder if that would just make things way too annoying to keep swapping out the cards to upgrade each class one at a time. Although generally speaking, a new tech only unlocks an upgrade for a single unit type, so it would somewhat make sense to handle it that way.

But yeah, late game costs are definitely crazy. As you said, they were originally based on factory stacking, but never really dropped down. They cut district costs and that has helped a lot, but buildings and units are still way too expensive for the bonuses they yield, especially for the T3 buildings.

 

[kaspergm]

Yeah, I agree with most of this. Upgrading is too cheap relative to building, but whether you fix that by reducing building costs, or increasing upgrade costs, both valid.

Just want to throw in that while it's true that increasing upgrade cost and reducing production cost will give the same relative balance change, they will not be the same in terms of overall game impact. Increasing upgrade cost will slow an (imo.) already too slow game down, while decreasing production cost will have the opposite overall effect.

 

[sixty4half]

A combination of these 2 suggestions would be good. The idea that you have a cap on units, so you actually need to invest in the key factors for making war. ie Military encampments and population to field an army.
It would actually encourage 2 other factors of the game that are currently less important, growing your cities and building encampments, both of which are currently less important than pumping out units. And because of one unit per tile, I wouldn't mind seeing other limits. Such as, if you build too many units in a city you lose population points. If you are sending that many of your men off to fight then you are going to drop your productivity at some point.

All these things also track historically, being seen over and over again.

There is a massive problem with ideas like these though. It sounds great in theory, have a cap on units tied to military buildings, number of cities, and population. However; what happens when you have 1 city with 2 pop and no techs to even build an encampment? Barbarians happen. And you have 1 or 2 units.

So then you make a caveat; each city can support 2 units with each population supporting an additional 1? That sounds balanced for the early game? A 2 pop capital can have 4 units. You could build an invasion force of 6 units once you hit 4 pop. But what does that look like in the mid game when we have 10 cities with 4-12 pop apiece? Then the cap begins to just look silly because that is already a ridiculous amount of units.

Even on a sliding scale, where each additional city or pop counts for less cap space, it's still a lot of units once you get to that amount of cities. So there are two problems preventing this from happening as I see it. The early aggression of AI and the way barbarians spawn currently in the early game, and the ICS that invariable happens in the midgame of Civ 6. Only if barbarians were toned down and something was done to prevent everyone dropping 12 cities even on a Tiny map could this kind of system work.

 

[acluewithout]

There is a massive problem with ideas like these though. It sounds great in theory, have a cap on units tied to military buildings, number of cities, and population. However; what happens when you have 1 city with 2 pop and no techs to even build an encampment? Barbarians happen. And you have 1 or 2 units.

So then you make a caveat; each city can support 2 units with each population supporting an additional 1? That sounds balanced for the early game? A 2 pop capital can have 4 units. You could build an invasion force of 6 units once you hit 4 pop. But what does that look like in the mid game when we have 10 cities with 4-12 pop apiece? Then the cap begins to just look silly because that is already a ridiculous amount of units.

Even on a sliding scale, where each additional city or pop counts for less cap space, it's still a lot of units once you get to that amount of cities. So there are two problems preventing this from happening as I see it. The early aggression of AI and the way barbarians spawn currently in the early game, and the ICS that invariable happens in the midgame of Civ 6. Only if barbarians were toned down and something was done to prevent everyone dropping 12 cities even on a Tiny map could this kind of system work.

Well, you might well be right.

But my thinking was how much force limit a unit used up would increase depending on the type of unit and its era. So, heavy cav would eat up more force limit than say melee, and tanks would use up more than knights. On that basis, I don’t think the cap would really bite until mid to late game, by which time you’re hopefully ready for the game to force you to make some choices about what units comprise your military. Early game you’d be okay no matter what.

It would also be a soft cap, so that you could go over your cap but that might hurt parts of your economy. You’d also have policy cards that would give you some flex. So, hordes of barbs would be manageable. You could also always just by city state units (and indeed, maybe “mercenaries” would be more available generally).

Really, this is sort of what maintenance is already getting at. It’s just that maintenance is just so weak for various reasons that it doesn’t actually create any hard decisions. Perhaps a really thoughtful overhaul of maintenance costs would be a better approach overall. I don’t know really.

I guess another approach would be to just stop
some units upgrading. I mean, maybe melee or anti-cav can upgrade forever, but perhaps Knight can’t go to tanks. Instead, if you want tanks, you retire your knights (for gold) and build tanks from new. That might be a little more attractive if promotion levels gave you more gold (or maybe culture). But I could see that creating lots of other problems too. People might just not build anything except melee or anti-cav. As it is, hard building unique units or aircraft isn’t hugely attractive (although I do sometimes hard build Artillery).

My basic point is that the game needs some restrictions on unit spam (with upgrading being kind of an aspect of unit spam). In the real world, military investment goes up and down over time. In Civ, you just (over) invest at the start, and you’re basically done.