Please don't flame me for this. But this is my vision for Civ 6 :|
0. 1 turn= 1 year? That is a bit too much, but 1 turn should not allow you to jump a lot of years (even in early game). I will talk more about this in just a few moments.
1. Global food supply:
Start of the game: Each city produces it's own food.
Roads: Can distribute food to cities up to 4/6/8? tiles away
Railroads: Can distribute food to cities up to 8/10/12 tiles away? (optionally also requires direct railroad connection to the city... not through some other city)
Refrigeration: Can distribute food to cities 25/30 tiles away
(Flight or Freight)+Refrigeration: True global food supply.
Pros: By the industrial age, you can have dedicated cities producing food. This is more realistic and makes the end game more manageable. The starting game is still similar to what we have right now. Also, we now get a concept of key "strongholds". Lose your grain baskets and your jeopardize your whole empire!
2. Solve 1UTP and SOD: 1UTP leads to "carpet of doom" (that is one unit in each hex). However, 1UTP was created to solve SOD. Here is another solution to solve SOD and also have a more realistic army size.
2a. Max stack level: A city occupies one hex. In game terms, that means one hex is a large area. Therefore if you have only 1 unit in that area, it looks weird. Allow, say up to 5/6/7/8 units in that one hex. (expanding on this...)
2b. A stack has a defense rating. If you have a good mix of units, like ranged + melee + siege etc, its defense is considered to be higher than a stack with just ranged or siege. A stack of siege for instance, should have a defense rating of 0 and can be butchered by melee units etc. This way you can not have a SOD, with many unit types. Also stacks should be expensive to maintain (read more on this below). This will prevent stack spam. Having all melee units is also bad. Other players can take them out with a good combination of ranged + melee.
2c. A stack should be vulnerable to flanking. So when you position your stack of units on a hex, you also choose what hex they face. Attack from a stack that is "behind" them or on their "left or right" side should incur a defense penalty
2d. A city can have one stack of army protecting them. However, a building like an army base should allow up to 5-6 stacks of army units. Army bases should be expensive with a very high upkeep, to prevent spamming them in every city. The more stacks of units in a base, the more it would cost to maintain
2e. Variable army maintenance cost: If your "stacks" are garrisoned in a base, they will cost, say 3 gold to maintain. However, the moment they leave the garrison, the maintenance cost doubles (or triples?) (that is mobilizing your army/war is expensive). This forces the players to build a strong economy before waging war. This prevents early rushes and makes the game more realistic. Waging war should be expensive.
2f. Foreign army bases: A protection pact with foreign civilization allows you to build army bases in a foreign city. These appear outside the city and allow up to 4 stacks of unit. The cost of garrisoning units in these bases is more than what it would cost you to garrison units in your own base (in your cities). Cost of foreign base can be shared between you and the foreign civ, but army cost is all yours. This will also require changes to "diplomacy" (later on this).
2g. Faster army production: Units can be produced in 1-2 turns (even with low production). However, getting too many units = maintenance cost nightmare. So you can't have a super large army in the early game, unless you have an awesome gold supply. Even then it can be prevented with increasing the cost of maintenance as you produce more and more units
3. Trust + happiness: Depending on your social policies, war should have an impact on happiness. This impact should last the duration of the war and then 3-5 turns after you end the war (people remember the horrors of war!!!). Some "Policies" should reduce this impact (if you are a militaristic civ). Starting multiple wars should result in an exponential impact on your happiness. Also, initiating a war for no reason, should cause a large impact on your happiness.
3a. Trust rating: A new rating in Civ. This represents the amount of trust that your people have in you (local trust) and how much the other civilizations trust you (global trust). Good things raise this or keeps it flat (have a lot of city-state allies, not inciting war for "x" turns, going to war with a "reason for war" etc) and bad things (inciting wars, weakening economy, low culture, hungry population etc) lowers this. Once lowered, it takes several turns to rebuild this (say 20-35 turns). (More on this)
3b. Self-sabotage: Do something nasty to yourself and blame it on other people to incite a war. Affects your trust rating (people get suspicious). If your trust rating is high, happiness is not affected to such an extent. However, if you self-sabotage to start a war and your trust is low, happiness will take a large impact. Self-sabotage should be expensive. You should lose a building (randomly selected) and things like production + gold etc should take a hit in that city.
3c. Reason for war: A screen (like the diplomacy screen), where you talk to your council members/cabinet/house/senate etc. If you don't want to self-sabotage, you can convince them (through options on the screen) that a war is needed (maybe because you are going short on some resource that you want?). If you have a "reason for war", the happiness impact is greatly reduced (maybe down to 1?)
3d. Trust + happiness can somehow be programmed to be locked with the idea of "revolution". So therefore, if you try to wage a lot of war with low trust and low happiness, a revolution might be triggered. During this time, you need your army to be near your cities and not away, waging some war! Revolution spawn enemy units outside your cities that must be dealt with. Also during revolution, things like science, culture, production and gold takes a hit. Trust + happiness + variable army maintenance cost prevents constant war and forces you to focus on building your economy, culture, production, food up first.
Other things can also lead to a "revolution". For instance, if people are unhappy for many consecutive turns (30-40?) or short bursts of many turns, dwindling food output, a "sense" of weakening economy (for many turns (70-100?) etc. Need to flesh this out more properly.
3e. This is where 1 turn=1 year pictures in. You have a lot of time to wage wars, but you can't always be in a persistent state of war all the time. This will also require re-balancing research, production etc in the early years.
4. Diplomacy overhaul: Having foreign army bases and trust + happiness + reason for war, opens up a lot of diplomacy options.
4a. Civs can't just break up friendships etc without incurring a large cost (in gold+happiness+trust etc).
4b. A lot of additional diplomatic options: Pledge to protect carries some weight if you put an army base in the foreign country.
4c. Breaking up treaties etc will cause your "trust rating" to take a nosedive. Immediately declaring war (5-20 turns) after a friend treaty expires also causes trust to take a nosedive, causing it more difficult to incite new wars.
4d. The diplomacy system should take "trust" into account.
4e. The diplomacy routines in the AI should also take into account trade worth. If someone is trading valuable luxury/strategic resources, it would avoid war. More gold should come from "international trade" than from any other form! Waging war on a major trading partner can be disastrous for the economy. The downside of this is that games with fewer players will not be possible or extremely hard.
4f. Declaring war on a civ where you have a foreign base will have huge ramifications. Your global trust will go down and will remain down for 50-75 turns? Of course, a self-sabotage can help you here
5. City spam: This should be prevented by bringing back Civ 4's system of city upkeep. Newer cities require upon other cities to survive (economically and food wise). Creating lots of small cities can cause happiness + food + gold strain on your economy.
6. Better AI: We need better AI to get any of this done!!!! (stating the obvious)
7. I love the idea of "super-civs". That is something akin to European Union. Need some "industrial era" tech or policy to unlock ("New World Order"?)
7a. New victory condition - The Great Union: Create a super-state
7b. 2 or more civs can create a super-state. More civs are able to join after a voting process. Max of 3 (or 4 if lots of players on map) allowed in a super-state.
7c. Super-state capital different from civ's own capital. Gets special bonus to "Defense", and gets a burst in gold production. Extra gold distributed to all civs.
7d. Civs can leave super-state. But can't be hasty about this, because it can have an effect on trust+happiness as well as economical implications.
7e. Different levels in the unions:
Economic unity: Super-state capital generates extra gold, that is shared across other civs in super-state
Border unity: Open borders for all civs
Military unity: Civs operate their own army, but cost is shared by everyone for all things including army bases
7f. Will need to address a lot of imbalance issues: Mainly, a super-state can overwhelm non-super states. Therefore, trust and happiness take bigger hits. Individual civs in super-state need their own "reason for war" (read point 3c) to join the war. Individual civs go to their own wars (the super-state does not need to join). Also, if a war is started alone (without the approval of super-state), during the duration of the war (and 10 turns after it ends), the cost of one's military is shared by one's own-self (even though you might have Military Unity). Reason of war can be expanded to convince both your own council/cabinet/senate and super-state senate.
7g. This idea needs to be fleshed out more....
8. Religion needs to be brought back in some form. Haven't thought a lot about this though.
9. Better UN: Combined with super-states, trust, happiness, the newer diplomacy model, UN can actually be a powerful thing! Haven't thought about this much though, other than somehow going to war with allies.
0. 1 turn= 1 year? That is a bit too much, but 1 turn should not allow you to jump a lot of years (even in early game). I will talk more about this in just a few moments.
1. Global food supply:
Start of the game: Each city produces it's own food.
Roads: Can distribute food to cities up to 4/6/8? tiles away
Railroads: Can distribute food to cities up to 8/10/12 tiles away? (optionally also requires direct railroad connection to the city... not through some other city)
Refrigeration: Can distribute food to cities 25/30 tiles away
(Flight or Freight)+Refrigeration: True global food supply.
Pros: By the industrial age, you can have dedicated cities producing food. This is more realistic and makes the end game more manageable. The starting game is still similar to what we have right now. Also, we now get a concept of key "strongholds". Lose your grain baskets and your jeopardize your whole empire!
2. Solve 1UTP and SOD: 1UTP leads to "carpet of doom" (that is one unit in each hex). However, 1UTP was created to solve SOD. Here is another solution to solve SOD and also have a more realistic army size.
2a. Max stack level: A city occupies one hex. In game terms, that means one hex is a large area. Therefore if you have only 1 unit in that area, it looks weird. Allow, say up to 5/6/7/8 units in that one hex. (expanding on this...)
2b. A stack has a defense rating. If you have a good mix of units, like ranged + melee + siege etc, its defense is considered to be higher than a stack with just ranged or siege. A stack of siege for instance, should have a defense rating of 0 and can be butchered by melee units etc. This way you can not have a SOD, with many unit types. Also stacks should be expensive to maintain (read more on this below). This will prevent stack spam. Having all melee units is also bad. Other players can take them out with a good combination of ranged + melee.
2c. A stack should be vulnerable to flanking. So when you position your stack of units on a hex, you also choose what hex they face. Attack from a stack that is "behind" them or on their "left or right" side should incur a defense penalty
2d. A city can have one stack of army protecting them. However, a building like an army base should allow up to 5-6 stacks of army units. Army bases should be expensive with a very high upkeep, to prevent spamming them in every city. The more stacks of units in a base, the more it would cost to maintain
2e. Variable army maintenance cost: If your "stacks" are garrisoned in a base, they will cost, say 3 gold to maintain. However, the moment they leave the garrison, the maintenance cost doubles (or triples?) (that is mobilizing your army/war is expensive). This forces the players to build a strong economy before waging war. This prevents early rushes and makes the game more realistic. Waging war should be expensive.
2f. Foreign army bases: A protection pact with foreign civilization allows you to build army bases in a foreign city. These appear outside the city and allow up to 4 stacks of unit. The cost of garrisoning units in these bases is more than what it would cost you to garrison units in your own base (in your cities). Cost of foreign base can be shared between you and the foreign civ, but army cost is all yours. This will also require changes to "diplomacy" (later on this).
2g. Faster army production: Units can be produced in 1-2 turns (even with low production). However, getting too many units = maintenance cost nightmare. So you can't have a super large army in the early game, unless you have an awesome gold supply. Even then it can be prevented with increasing the cost of maintenance as you produce more and more units
3. Trust + happiness: Depending on your social policies, war should have an impact on happiness. This impact should last the duration of the war and then 3-5 turns after you end the war (people remember the horrors of war!!!). Some "Policies" should reduce this impact (if you are a militaristic civ). Starting multiple wars should result in an exponential impact on your happiness. Also, initiating a war for no reason, should cause a large impact on your happiness.
3a. Trust rating: A new rating in Civ. This represents the amount of trust that your people have in you (local trust) and how much the other civilizations trust you (global trust). Good things raise this or keeps it flat (have a lot of city-state allies, not inciting war for "x" turns, going to war with a "reason for war" etc) and bad things (inciting wars, weakening economy, low culture, hungry population etc) lowers this. Once lowered, it takes several turns to rebuild this (say 20-35 turns). (More on this)
3b. Self-sabotage: Do something nasty to yourself and blame it on other people to incite a war. Affects your trust rating (people get suspicious). If your trust rating is high, happiness is not affected to such an extent. However, if you self-sabotage to start a war and your trust is low, happiness will take a large impact. Self-sabotage should be expensive. You should lose a building (randomly selected) and things like production + gold etc should take a hit in that city.
3c. Reason for war: A screen (like the diplomacy screen), where you talk to your council members/cabinet/house/senate etc. If you don't want to self-sabotage, you can convince them (through options on the screen) that a war is needed (maybe because you are going short on some resource that you want?). If you have a "reason for war", the happiness impact is greatly reduced (maybe down to 1?)
3d. Trust + happiness can somehow be programmed to be locked with the idea of "revolution". So therefore, if you try to wage a lot of war with low trust and low happiness, a revolution might be triggered. During this time, you need your army to be near your cities and not away, waging some war! Revolution spawn enemy units outside your cities that must be dealt with. Also during revolution, things like science, culture, production and gold takes a hit. Trust + happiness + variable army maintenance cost prevents constant war and forces you to focus on building your economy, culture, production, food up first.
Other things can also lead to a "revolution". For instance, if people are unhappy for many consecutive turns (30-40?) or short bursts of many turns, dwindling food output, a "sense" of weakening economy (for many turns (70-100?) etc. Need to flesh this out more properly.
3e. This is where 1 turn=1 year pictures in. You have a lot of time to wage wars, but you can't always be in a persistent state of war all the time. This will also require re-balancing research, production etc in the early years.
4. Diplomacy overhaul: Having foreign army bases and trust + happiness + reason for war, opens up a lot of diplomacy options.
4a. Civs can't just break up friendships etc without incurring a large cost (in gold+happiness+trust etc).
4b. A lot of additional diplomatic options: Pledge to protect carries some weight if you put an army base in the foreign country.
4c. Breaking up treaties etc will cause your "trust rating" to take a nosedive. Immediately declaring war (5-20 turns) after a friend treaty expires also causes trust to take a nosedive, causing it more difficult to incite new wars.
4d. The diplomacy system should take "trust" into account.
4e. The diplomacy routines in the AI should also take into account trade worth. If someone is trading valuable luxury/strategic resources, it would avoid war. More gold should come from "international trade" than from any other form! Waging war on a major trading partner can be disastrous for the economy. The downside of this is that games with fewer players will not be possible or extremely hard.
4f. Declaring war on a civ where you have a foreign base will have huge ramifications. Your global trust will go down and will remain down for 50-75 turns? Of course, a self-sabotage can help you here

5. City spam: This should be prevented by bringing back Civ 4's system of city upkeep. Newer cities require upon other cities to survive (economically and food wise). Creating lots of small cities can cause happiness + food + gold strain on your economy.
6. Better AI: We need better AI to get any of this done!!!! (stating the obvious)
7. I love the idea of "super-civs". That is something akin to European Union. Need some "industrial era" tech or policy to unlock ("New World Order"?)
7a. New victory condition - The Great Union: Create a super-state
7b. 2 or more civs can create a super-state. More civs are able to join after a voting process. Max of 3 (or 4 if lots of players on map) allowed in a super-state.
7c. Super-state capital different from civ's own capital. Gets special bonus to "Defense", and gets a burst in gold production. Extra gold distributed to all civs.
7d. Civs can leave super-state. But can't be hasty about this, because it can have an effect on trust+happiness as well as economical implications.
7e. Different levels in the unions:
Economic unity: Super-state capital generates extra gold, that is shared across other civs in super-state
Border unity: Open borders for all civs
Military unity: Civs operate their own army, but cost is shared by everyone for all things including army bases
7f. Will need to address a lot of imbalance issues: Mainly, a super-state can overwhelm non-super states. Therefore, trust and happiness take bigger hits. Individual civs in super-state need their own "reason for war" (read point 3c) to join the war. Individual civs go to their own wars (the super-state does not need to join). Also, if a war is started alone (without the approval of super-state), during the duration of the war (and 10 turns after it ends), the cost of one's military is shared by one's own-self (even though you might have Military Unity). Reason of war can be expanded to convince both your own council/cabinet/senate and super-state senate.
7g. This idea needs to be fleshed out more....
8. Religion needs to be brought back in some form. Haven't thought a lot about this though.
9. Better UN: Combined with super-states, trust, happiness, the newer diplomacy model, UN can actually be a powerful thing! Haven't thought about this much though, other than somehow going to war with allies.