I feel we've extensively discussed all the possible ways Civ 7 could be reformed with major and minor overhauls to the game. After all the discussion, while I think there are a lot of interesting ideas, some I prefer, and some which I feel are necessary for Firaxis to pursue from a marketing perspective (get rid of hard age switching, classic mode), I don't think we'll get that.
At this point, there's only one thing I think Firaxis would actually do that can possibly save the game. This is simply making the legacy paths much more in depth and fun for each age. Now, for the purposes of this discussion let's assume that a lot of the wider overhead issues will be taken care of, which is a lot to assume. Better UI, reduced bugs, better QoL, and introduction and refinement of features like balancing diplomacy, smoothing age transitions in line with the direction they're already going.
I also think major depth needs to be added in a free patch, or else people will not purchase the DLC that introduces it because that's too cynical. UI overhaul and balances need to be free patch. And also legacy depth. For instance, if they improve religion, that should be a free patch, and then a system built on it like religious wars should be in the DLC.
What improvements would you make, if it's just a matter of adding depth to legacy paths? Also, if there's a clear and major balancing, say to the diplomacy AI, feel free to mention that too. I would make it so resources don't disappear anymore on age change, for one. I'd add an automated city growth feature, I can think of a few simple algorithms for it and it's no different than a city governor. I'd also have some option to de-improve tiles, and though I'm not sure the exact direction without overcomplicating things, I'd tone down specialists and maybe find some other use for food growth meta such as building city infrastructure.
Actually, let's reset on that. I'd tone down how strong specialists are, and many of you have proposed great parameters for this. However, I'd add "Great Specialists" or something. So you spend 2 saved up specialist points to create a "City Praetor" who manages the sewage system, or "sanitation specialist" in modern. Which gives a macro buff to your city. This is a rather major adjustment to the game, but there would be no visual assets added, just maybe one UI screen plus some balancing work.
I'd also change how commander ranks work, simplifying it (and the attribute tree for that matter, toning down the attribute tree to prevent snowballing). I'd do a system where commander experience becomes empire-wide accumulated military acumen, and individual commanders can be retrained with specific skills with an auto-recall to train then return type system. This seems like the perfect addition to the tactical logistics. You can reskill a commander if you have a few turns without having to totally reposition an army. You could have abilities and buildings, civics that boost this system.
For legacy paths, I'd get rid of the quest style system and just put the tutorial info in the civilopedia. Now these are just victory conditions. I'd make legacy rewards clearer by listing them in the civilopedia. If possible, I'd link legacy results to legacy requirements in later ages. So, for instance, a specific legacy bonus earned in Antiquity for Exploration unlocks and Exploration to Modern bonus that you can't get if you don't first choose that first bonus. These chained bonuses will be listed clearly in the civilopedia, and chained bonuses will be a whole thing with legacy trees. You ought to be able to pick hybrid bonuses for getting multiple legacy victories or some for being in the top 3 in an age. This kind of strategic depth, paired of course again with muting the efficacy of specialists and the attribute tree. Let snowballing result from strategic choice of legacy victories and chained bonuses. The snowballing doesn't come from your bonus, but rather how that bonus works with your strategy and the empire you've built.
I intend this thread to be constructive not about ideas or hopes for Civ 7, but identifying where there is fun in the Civ 7 formula-as-is that can be expanded through depth, and also identifying what sort of depth would simply not work or be helpful. I'd hope this might guide marketing and development considerations for the game by starting a set of discussions in that direction, in hopes of being constructive rather than pessimistic about this game.
To start it off, here's how I'd do the legacy changes:
Antiquity
Military: Based on score, not city capture (antiquity is too early for pure domination, which would lead to a snowball, it shouldn't be directly encouraged). Score comes from commander experience gained, and K/D ratios in battles. Maybe there can be a set of 5-10 achievements in the victory menu called "feats" which tie military victory more to generating heroic epics, something like Thermopylae is as meaningful as conquering the world. Still, a 100% conquest will trigger a game win and age progression will stop. Conquest will be considered a different category than military legacy victory.
Economic: Total empire resources, city score based on resource deep cities plus the number of them at a given time (height of resource power vs breadth), and a trade score. I'd also deepen the trade system with improve road building, trade routing, and gold from trade contributing to the score.
Cultural: Pilgrimage system, internal to empire only. Wonders, pantheon, then general cultural buildings plus city connections generate a pilgrimage score per city. Pilgrims also improve happiness AND can be traded-off with happiness to accelerate wonder construction (put those pilgrims to work!). Get the idea? This system will become external in the next age and influence religious spread.
Scientific: Generally the same except codices can be traded away to foreign powers to pick up technologies from them. Also, codices will endure to the Exploration Age and have a function there, so there's a little strategic planning involved.
Exploration
Military: Similar to antiquity. Siege warfare system expanded with points accumulated based on siege length (but siege induces a happiness and food cost to cities, so it's not enough to hide behind your walls, merely facing a siege will impose costs on that specific city). So, there's a city limited (not empire wide) war weariness for defenders but defenders gain some military victory points so a strategic trade-off to doing a siege. Finally, there's a tourney system now where idle commanders can be sent away for many turns to fight in tourneys which can gain military points (chivalric prestige) but based on other players joining the tourney and and commander rank or something. The tourney can actually help you win the legacy path, so you'd be tempted to send all your commanders there, but then you'd be vulnerable to attack and losing cities might be a lot worse. When you unlock "Sovereignty" as a civic, picking up new settlements will finally now grant military points.
Economic: Explorers can now create trade outposts - 1-tile radius pseudo-settlements with civ specific outpost types. These allow resource exploitation without a settlement and provide some other bonuses. Typically, a light defensive bonus so they also function as forts. A civ like Spain can build missions which are outposts but with also a religious bonus of some kind like spread pressure. Now we have land based treasure ships so that's great. Outposts can generate them and treasure ships if coastal.
Cultural: Fix religion. Make initial conversion much more important than later pressure. Have a pressure system. More depth can wait for the expansion (apostles, crusaders, inquisitors, scholastics). Allow non-founders to receive a non-founder benefit from a religion, making just giving up and accepting a rival's religion a legitimate option. Integrate this with diplomacy, one single friendship parameter for shared religion. Finally, relics can now be traded and also slotted into either culture buildings (for religious victory points) or other buildings (using religion to help in other areas: food, gold, science). This means religion can be pursued as a way to win other victories instead of just cultural. There are still pilgrims, but now they go externally as well. Exploration Age wonders affect them, opening the door for pilgrimage specific wonders of which there are MANY in human culture. Pilgrims affect religious pressure, and trade opens the door to pilgrims externally, but new civ policies can interact with this. After initial conversion, pilgrims are more important to religious conversion than more missionary work, but missionaries can put key cities over the edge. You might missionary spam, but to a key city not ALL of them. Escalating missionary costs balances people who have an early lead from converting everyone. Religious bonuses are boosted a bit assuming you're just not going to convert as many people as you could with missionary staging for end-of-age total conversion.
Scientific: First, codices endure to the early Exploration. There will be events, as religion develops, which demand you destroy codices. If you don't, there's a huge happiness penalty with long cooldown. You can also destroy codices to increase religious pressure in a city. I dislike science in Exploration. It's all about being very specific adjacencies, and being highly constrained in specialist placement and I don't really like specialists. What characterized scientific excellence in the renaissance/enlightenment? I think you need to just have victory points again, and you accumulate them with: having the right civics (humanism, rationalism) which reduce the efficacy of your religious bonuses, having LOTS of trade (multiplicative, as you gain more science points, your trade partners do to if they are also pursuing science) which means peace over war, and funding science with lots of gold (not as a project, one time payments) which provides a mild science yield boost but massive victory point yields. This victory requires trading off almost everything for science but even attempting it, even if you don't win the legacy, will give very important science bonuses for Modern.
Modern
Military: Based on ideological victory after the ideology/world wars play out. Add in an alliance trigger which forces all powers to choose an alignment even though you can align without embracing that ideology, you can also attempt neutrality. You would now have "Neutral Modernism" as a fourth ideological position. However, the conquest victory is reduced to all world capitals and 80% of cities from 100%. Experience balances so that you're maxxing out your commander attributes in this age and by the end of the age there's no valor based military advantages, just technology. Operation Ivy is removed, it's the same thing as both crewed rocket and manhattan project.
Economic: Factories are now tied to a corporation system that has supply and demand. Policies like monopolistic competition can accrue bonuses based on accumulated production, that gives you advantages over the supply/demand equilibrium. Autarky can cut off your production from global supply/demand, at the cost of being cut off from foreign resources, but gaining substantially more gold from your factory production. The victory now comes through an actual World Bank. Every turn you do more global commerce in gold amounts than others, you accumulate "foreign reserves" from each country based on relative trade performance per turn. As you accumulate "foreign reserves" a small amount of gold transfers from those countries to yours based on the amount of reserves. Thus, Autarky makes a smaller commercial power wealthier, but really small powers need the access to resources and have to suffer the costs living under economic hegemony. Meanwhile, commercial giants will begin to leech massive gold from other countries helping them make purchases but also at some point at enough reserves from enough powers, they win the victory (bretton woods conference or something). I think there should be a "demand open trade" option to counter Autarky policies, in diplomacy, and it triggers war if there isn't already war, or you can add it to existing war. When peace is declared, an enemy must automatically drop Autarky AND contribute a large chunk of reserves and automatic trade routes. So, economic victory can overlap with world wars, but doesn't have to.
Cultural: Diplomatic permission for explorers, meaning a possible need to declare war and protect explorers to gain artifacts. Relics and Codices count toward World's Fair. World's Fair event occurs after 20-50 turns. Winners of the fair get first come first serve access to modern cultural policies. Radio stations and other policies create cultural pressure. Pilgrimage system remains, but features like radio boost victory yields. Commerce is deeply tied to cultural victory yields as well.
Scientific: Scientific great persons. Trade + Science yields X specific policies and buildings X certain wonders X diplomatic deals (initiatives you only get if you had some success on the last age science path). This formula accumulates towards great persons, which boost a specific scientific victory tree (not the technology tree) for multiple players based on the diplomatic initiative. This tree gatekeeps buildings and units even if you unlock tech tree nodes. The reason why is that progress in scientific victory trees is collective, based on diplomacy usually ideology clusters, so you'll progress in it faster than in the tech tree usually, but you can bee line the science tree for certain strategies. The Modern Age is all about global interconnectivity. This is the importance of science progress in Exploration, it unlocks the diplomatic initiative early.
For DLC 1 I'd add a medieval age to split from exploration. I'd add a crusades system and expand religion to have not just apostle/inquistors, but other units like scholastics, Confucian scholars, Jesuits (who can affect science, trade or diplomacy, with the addition now of an actual faith yield tied to this). I'd add a greater variety of military units with more tactical variety. Religion will be more complex with more nuanced social policies drawn from historical beliefs and practices. Religions will have variety where some can play well with other religions and other create unhappiness within plurality. This feature would not be a "crisis policy" but a feature of specific religious beliefs.
I'd then expand Exploration by adding in a colonial warehouse system. I'd add a new warehouse type building, the colonial warehouse. This can "receive" treasure wagons or ships, but then generate merchant ships. Treasure ships can still return home with the same effect, but if you do convert them to colonial resources in the warehouse, merchant ships trade colonial resources for colonial supplies, which is a way to get more gold in the end and boost growth in colonial settlements. There will be specific colonial resources and specific colonial supplies you can slot with specific effects, creating a mini SM Colonization in this Age. I'd expand the enlightenment system and put in an entire Age-long religious reformation process which is the new analogue for religious wars.
I'd add national gods for antiquity where you pick up more than one if you want, with a chief god you assign. These tie to specific bonuses. The game will naturally spawn "Pantheons" by smushing national gods in proximity together. You can spend faith to get your god included or other gods excluded. There will end up being 3-7 pantheons based on map size. Some gods can exist in multiple pantheons. Wonders, civics and faith expense can add new national gods, and each city can be assigned a specific one. You also choose a pantheon once you research polytheism. It doesn't have to overlap with your god, but your urban assigned gods need to be in your chosen pantheon to get a happiness bonus. Pantheons will gain an orientation based on included gods: militaristic, etc. Your diplomatic relations will be affected by shared Pantheon OR if your chief god happens to be in their Pantheon. It is possible to be between two Pantheons geographically and spend faith to join a totally unique pantheon. When you join or change pantheons, there's usually a list of a few options to choose from generated from local conditions. Pantheons also can have enemy gods like Ahuras vs. Daevas. This affects military points, where a victory of a chief god over an enemy pantheon grants military points, maybe cultural yields, experience boosts.
For modern, just add more unit complexity for the war, maybe some buffs to the science system.
For DLC 2 I'd expand the culture system in Modern by adding movie studios which are historic (like MGM or Lumiere Brothers) that are claimed first come first serve like religious beliefs. Then movies can be produced, screened in theaters, and even diplomatic initiatives let other players get culture tree yields from your movies at the cost of you getting victory points. I'd add a cultural victory element to commerce with national products you can bind to your corporations (like Coca-Cola).
Add the Post-Modern Age, which is a whole other discussion, but largely there is a lot less military conquest (but plenty of tactical fighting in proxy wars which score military points less for conquest and more for defeat of forces) Expanded diplomacy with shadow/cold wars, a NATO/Warsaw Pact system, you don't really conquer cities anymore (unless you're non-aligned), but huge spycraft system. The massive culture system from Modern that's been added carries over directly into Post-Modern. Economics is about having ownership over global shipping port "strategic" wonders without conquering that nation itself, a technology economy layer too. World War III is always on the table with ICBMs, but it's a drop everything all hell's loose kind of thing. Sort of like a you can't be "half pregnant". You'll either have minimal war and a regular game, or WWIII will happen and you disregard almost everything else for that Age. With a possibility of no winners, like an inverse conquest victory MAD scenario.
Mainly, Post-Modern Age is about spycraft and influence interacting with culture and economics in a deeply integrated way. It's all asymmetric. Sometimes culture trades for influence. Sometimes influence trades for gold. It also extends to the 2050s and a good deal of speculative future tech.
DLC 3/B.E. Sequel Game would be updates to the post-modern age to "fix" it, plus an "Age of Space" with hypothetical future Earth polities similar to Alpha Centauri but with echoes to history. "Neo-Roman Patriarchate", "Panhellenic Science League", "Tian Dynasty". This includes Lagrange colonies, Moon, Mars and other maps for Jovian moons. An attempt at space combat. Ocean floor colonization. Alpha Centauri style geo-modification of Earth. This will be more optimistic than Civ traditionally is where global warming is either mitigated, reversed, or simply adapted to, and Earth civilization endures pursuing strange divergent paths while trying to colonize the solar system. In other words, we will drop the "End of History" theology of the 1990s.
This will be a full game, but with the unique feature that it will carry over your Civ 7 saves to "keep playing" (so, if age transitions are smoothed out for Civ 7, this post-modern to space age transition will be a lot harder and cleaner, Post-Modern will be more of a final victory Age, and the "Space Age" will not be a 125 turn age but a full 300 age game). The other cool feature is that the development of this sequel game will included resources towards a few more patches and fixes for Civ 7. Including exclusive additions to the Post-Modern Age that you only get if you buy the sequel game (which integrate them, possibly early lunar/martian wars).
At this point, there's only one thing I think Firaxis would actually do that can possibly save the game. This is simply making the legacy paths much more in depth and fun for each age. Now, for the purposes of this discussion let's assume that a lot of the wider overhead issues will be taken care of, which is a lot to assume. Better UI, reduced bugs, better QoL, and introduction and refinement of features like balancing diplomacy, smoothing age transitions in line with the direction they're already going.
I also think major depth needs to be added in a free patch, or else people will not purchase the DLC that introduces it because that's too cynical. UI overhaul and balances need to be free patch. And also legacy depth. For instance, if they improve religion, that should be a free patch, and then a system built on it like religious wars should be in the DLC.
What improvements would you make, if it's just a matter of adding depth to legacy paths? Also, if there's a clear and major balancing, say to the diplomacy AI, feel free to mention that too. I would make it so resources don't disappear anymore on age change, for one. I'd add an automated city growth feature, I can think of a few simple algorithms for it and it's no different than a city governor. I'd also have some option to de-improve tiles, and though I'm not sure the exact direction without overcomplicating things, I'd tone down specialists and maybe find some other use for food growth meta such as building city infrastructure.
Actually, let's reset on that. I'd tone down how strong specialists are, and many of you have proposed great parameters for this. However, I'd add "Great Specialists" or something. So you spend 2 saved up specialist points to create a "City Praetor" who manages the sewage system, or "sanitation specialist" in modern. Which gives a macro buff to your city. This is a rather major adjustment to the game, but there would be no visual assets added, just maybe one UI screen plus some balancing work.
I'd also change how commander ranks work, simplifying it (and the attribute tree for that matter, toning down the attribute tree to prevent snowballing). I'd do a system where commander experience becomes empire-wide accumulated military acumen, and individual commanders can be retrained with specific skills with an auto-recall to train then return type system. This seems like the perfect addition to the tactical logistics. You can reskill a commander if you have a few turns without having to totally reposition an army. You could have abilities and buildings, civics that boost this system.
For legacy paths, I'd get rid of the quest style system and just put the tutorial info in the civilopedia. Now these are just victory conditions. I'd make legacy rewards clearer by listing them in the civilopedia. If possible, I'd link legacy results to legacy requirements in later ages. So, for instance, a specific legacy bonus earned in Antiquity for Exploration unlocks and Exploration to Modern bonus that you can't get if you don't first choose that first bonus. These chained bonuses will be listed clearly in the civilopedia, and chained bonuses will be a whole thing with legacy trees. You ought to be able to pick hybrid bonuses for getting multiple legacy victories or some for being in the top 3 in an age. This kind of strategic depth, paired of course again with muting the efficacy of specialists and the attribute tree. Let snowballing result from strategic choice of legacy victories and chained bonuses. The snowballing doesn't come from your bonus, but rather how that bonus works with your strategy and the empire you've built.
I intend this thread to be constructive not about ideas or hopes for Civ 7, but identifying where there is fun in the Civ 7 formula-as-is that can be expanded through depth, and also identifying what sort of depth would simply not work or be helpful. I'd hope this might guide marketing and development considerations for the game by starting a set of discussions in that direction, in hopes of being constructive rather than pessimistic about this game.
To start it off, here's how I'd do the legacy changes:
Antiquity
Military: Based on score, not city capture (antiquity is too early for pure domination, which would lead to a snowball, it shouldn't be directly encouraged). Score comes from commander experience gained, and K/D ratios in battles. Maybe there can be a set of 5-10 achievements in the victory menu called "feats" which tie military victory more to generating heroic epics, something like Thermopylae is as meaningful as conquering the world. Still, a 100% conquest will trigger a game win and age progression will stop. Conquest will be considered a different category than military legacy victory.
Economic: Total empire resources, city score based on resource deep cities plus the number of them at a given time (height of resource power vs breadth), and a trade score. I'd also deepen the trade system with improve road building, trade routing, and gold from trade contributing to the score.
Cultural: Pilgrimage system, internal to empire only. Wonders, pantheon, then general cultural buildings plus city connections generate a pilgrimage score per city. Pilgrims also improve happiness AND can be traded-off with happiness to accelerate wonder construction (put those pilgrims to work!). Get the idea? This system will become external in the next age and influence religious spread.
Scientific: Generally the same except codices can be traded away to foreign powers to pick up technologies from them. Also, codices will endure to the Exploration Age and have a function there, so there's a little strategic planning involved.
Exploration
Military: Similar to antiquity. Siege warfare system expanded with points accumulated based on siege length (but siege induces a happiness and food cost to cities, so it's not enough to hide behind your walls, merely facing a siege will impose costs on that specific city). So, there's a city limited (not empire wide) war weariness for defenders but defenders gain some military victory points so a strategic trade-off to doing a siege. Finally, there's a tourney system now where idle commanders can be sent away for many turns to fight in tourneys which can gain military points (chivalric prestige) but based on other players joining the tourney and and commander rank or something. The tourney can actually help you win the legacy path, so you'd be tempted to send all your commanders there, but then you'd be vulnerable to attack and losing cities might be a lot worse. When you unlock "Sovereignty" as a civic, picking up new settlements will finally now grant military points.
Economic: Explorers can now create trade outposts - 1-tile radius pseudo-settlements with civ specific outpost types. These allow resource exploitation without a settlement and provide some other bonuses. Typically, a light defensive bonus so they also function as forts. A civ like Spain can build missions which are outposts but with also a religious bonus of some kind like spread pressure. Now we have land based treasure ships so that's great. Outposts can generate them and treasure ships if coastal.
Cultural: Fix religion. Make initial conversion much more important than later pressure. Have a pressure system. More depth can wait for the expansion (apostles, crusaders, inquisitors, scholastics). Allow non-founders to receive a non-founder benefit from a religion, making just giving up and accepting a rival's religion a legitimate option. Integrate this with diplomacy, one single friendship parameter for shared religion. Finally, relics can now be traded and also slotted into either culture buildings (for religious victory points) or other buildings (using religion to help in other areas: food, gold, science). This means religion can be pursued as a way to win other victories instead of just cultural. There are still pilgrims, but now they go externally as well. Exploration Age wonders affect them, opening the door for pilgrimage specific wonders of which there are MANY in human culture. Pilgrims affect religious pressure, and trade opens the door to pilgrims externally, but new civ policies can interact with this. After initial conversion, pilgrims are more important to religious conversion than more missionary work, but missionaries can put key cities over the edge. You might missionary spam, but to a key city not ALL of them. Escalating missionary costs balances people who have an early lead from converting everyone. Religious bonuses are boosted a bit assuming you're just not going to convert as many people as you could with missionary staging for end-of-age total conversion.
Scientific: First, codices endure to the early Exploration. There will be events, as religion develops, which demand you destroy codices. If you don't, there's a huge happiness penalty with long cooldown. You can also destroy codices to increase religious pressure in a city. I dislike science in Exploration. It's all about being very specific adjacencies, and being highly constrained in specialist placement and I don't really like specialists. What characterized scientific excellence in the renaissance/enlightenment? I think you need to just have victory points again, and you accumulate them with: having the right civics (humanism, rationalism) which reduce the efficacy of your religious bonuses, having LOTS of trade (multiplicative, as you gain more science points, your trade partners do to if they are also pursuing science) which means peace over war, and funding science with lots of gold (not as a project, one time payments) which provides a mild science yield boost but massive victory point yields. This victory requires trading off almost everything for science but even attempting it, even if you don't win the legacy, will give very important science bonuses for Modern.
Modern
Military: Based on ideological victory after the ideology/world wars play out. Add in an alliance trigger which forces all powers to choose an alignment even though you can align without embracing that ideology, you can also attempt neutrality. You would now have "Neutral Modernism" as a fourth ideological position. However, the conquest victory is reduced to all world capitals and 80% of cities from 100%. Experience balances so that you're maxxing out your commander attributes in this age and by the end of the age there's no valor based military advantages, just technology. Operation Ivy is removed, it's the same thing as both crewed rocket and manhattan project.
Economic: Factories are now tied to a corporation system that has supply and demand. Policies like monopolistic competition can accrue bonuses based on accumulated production, that gives you advantages over the supply/demand equilibrium. Autarky can cut off your production from global supply/demand, at the cost of being cut off from foreign resources, but gaining substantially more gold from your factory production. The victory now comes through an actual World Bank. Every turn you do more global commerce in gold amounts than others, you accumulate "foreign reserves" from each country based on relative trade performance per turn. As you accumulate "foreign reserves" a small amount of gold transfers from those countries to yours based on the amount of reserves. Thus, Autarky makes a smaller commercial power wealthier, but really small powers need the access to resources and have to suffer the costs living under economic hegemony. Meanwhile, commercial giants will begin to leech massive gold from other countries helping them make purchases but also at some point at enough reserves from enough powers, they win the victory (bretton woods conference or something). I think there should be a "demand open trade" option to counter Autarky policies, in diplomacy, and it triggers war if there isn't already war, or you can add it to existing war. When peace is declared, an enemy must automatically drop Autarky AND contribute a large chunk of reserves and automatic trade routes. So, economic victory can overlap with world wars, but doesn't have to.
Cultural: Diplomatic permission for explorers, meaning a possible need to declare war and protect explorers to gain artifacts. Relics and Codices count toward World's Fair. World's Fair event occurs after 20-50 turns. Winners of the fair get first come first serve access to modern cultural policies. Radio stations and other policies create cultural pressure. Pilgrimage system remains, but features like radio boost victory yields. Commerce is deeply tied to cultural victory yields as well.
Scientific: Scientific great persons. Trade + Science yields X specific policies and buildings X certain wonders X diplomatic deals (initiatives you only get if you had some success on the last age science path). This formula accumulates towards great persons, which boost a specific scientific victory tree (not the technology tree) for multiple players based on the diplomatic initiative. This tree gatekeeps buildings and units even if you unlock tech tree nodes. The reason why is that progress in scientific victory trees is collective, based on diplomacy usually ideology clusters, so you'll progress in it faster than in the tech tree usually, but you can bee line the science tree for certain strategies. The Modern Age is all about global interconnectivity. This is the importance of science progress in Exploration, it unlocks the diplomatic initiative early.
For DLC 1 I'd add a medieval age to split from exploration. I'd add a crusades system and expand religion to have not just apostle/inquistors, but other units like scholastics, Confucian scholars, Jesuits (who can affect science, trade or diplomacy, with the addition now of an actual faith yield tied to this). I'd add a greater variety of military units with more tactical variety. Religion will be more complex with more nuanced social policies drawn from historical beliefs and practices. Religions will have variety where some can play well with other religions and other create unhappiness within plurality. This feature would not be a "crisis policy" but a feature of specific religious beliefs.
I'd then expand Exploration by adding in a colonial warehouse system. I'd add a new warehouse type building, the colonial warehouse. This can "receive" treasure wagons or ships, but then generate merchant ships. Treasure ships can still return home with the same effect, but if you do convert them to colonial resources in the warehouse, merchant ships trade colonial resources for colonial supplies, which is a way to get more gold in the end and boost growth in colonial settlements. There will be specific colonial resources and specific colonial supplies you can slot with specific effects, creating a mini SM Colonization in this Age. I'd expand the enlightenment system and put in an entire Age-long religious reformation process which is the new analogue for religious wars.
I'd add national gods for antiquity where you pick up more than one if you want, with a chief god you assign. These tie to specific bonuses. The game will naturally spawn "Pantheons" by smushing national gods in proximity together. You can spend faith to get your god included or other gods excluded. There will end up being 3-7 pantheons based on map size. Some gods can exist in multiple pantheons. Wonders, civics and faith expense can add new national gods, and each city can be assigned a specific one. You also choose a pantheon once you research polytheism. It doesn't have to overlap with your god, but your urban assigned gods need to be in your chosen pantheon to get a happiness bonus. Pantheons will gain an orientation based on included gods: militaristic, etc. Your diplomatic relations will be affected by shared Pantheon OR if your chief god happens to be in their Pantheon. It is possible to be between two Pantheons geographically and spend faith to join a totally unique pantheon. When you join or change pantheons, there's usually a list of a few options to choose from generated from local conditions. Pantheons also can have enemy gods like Ahuras vs. Daevas. This affects military points, where a victory of a chief god over an enemy pantheon grants military points, maybe cultural yields, experience boosts.
For modern, just add more unit complexity for the war, maybe some buffs to the science system.
For DLC 2 I'd expand the culture system in Modern by adding movie studios which are historic (like MGM or Lumiere Brothers) that are claimed first come first serve like religious beliefs. Then movies can be produced, screened in theaters, and even diplomatic initiatives let other players get culture tree yields from your movies at the cost of you getting victory points. I'd add a cultural victory element to commerce with national products you can bind to your corporations (like Coca-Cola).
Add the Post-Modern Age, which is a whole other discussion, but largely there is a lot less military conquest (but plenty of tactical fighting in proxy wars which score military points less for conquest and more for defeat of forces) Expanded diplomacy with shadow/cold wars, a NATO/Warsaw Pact system, you don't really conquer cities anymore (unless you're non-aligned), but huge spycraft system. The massive culture system from Modern that's been added carries over directly into Post-Modern. Economics is about having ownership over global shipping port "strategic" wonders without conquering that nation itself, a technology economy layer too. World War III is always on the table with ICBMs, but it's a drop everything all hell's loose kind of thing. Sort of like a you can't be "half pregnant". You'll either have minimal war and a regular game, or WWIII will happen and you disregard almost everything else for that Age. With a possibility of no winners, like an inverse conquest victory MAD scenario.
Mainly, Post-Modern Age is about spycraft and influence interacting with culture and economics in a deeply integrated way. It's all asymmetric. Sometimes culture trades for influence. Sometimes influence trades for gold. It also extends to the 2050s and a good deal of speculative future tech.
DLC 3/B.E. Sequel Game would be updates to the post-modern age to "fix" it, plus an "Age of Space" with hypothetical future Earth polities similar to Alpha Centauri but with echoes to history. "Neo-Roman Patriarchate", "Panhellenic Science League", "Tian Dynasty". This includes Lagrange colonies, Moon, Mars and other maps for Jovian moons. An attempt at space combat. Ocean floor colonization. Alpha Centauri style geo-modification of Earth. This will be more optimistic than Civ traditionally is where global warming is either mitigated, reversed, or simply adapted to, and Earth civilization endures pursuing strange divergent paths while trying to colonize the solar system. In other words, we will drop the "End of History" theology of the 1990s.
This will be a full game, but with the unique feature that it will carry over your Civ 7 saves to "keep playing" (so, if age transitions are smoothed out for Civ 7, this post-modern to space age transition will be a lot harder and cleaner, Post-Modern will be more of a final victory Age, and the "Space Age" will not be a 125 turn age but a full 300 age game). The other cool feature is that the development of this sequel game will included resources towards a few more patches and fixes for Civ 7. Including exclusive additions to the Post-Modern Age that you only get if you buy the sequel game (which integrate them, possibly early lunar/martian wars).
