I'm gonna indulge my amateur game designer/historian side for a moment and list the civs I would include in the vanilla game if I was making it, limiting myself to twenty starting civs.
Also I'm gonna try to nominate leaders who haven't appeared in Civ before. And I set myself an arbitrary quota of 20% female leaders.
Also I spent like three hours of serious thought on this, so please let me have it as its own thread. This isn't a "what civ you'd like to see" thread, this is a "which civs would you choose and what sort of play style you'd design them for and why" thread.
Here goes:
American
Leader: Theodore Roosevelt, as the guy most responsible for turning the United States into a Great Power, and fits quite well with my intended theme for the civ (see below)
Gameplay: It should be a challenging civ to play in the early game, but ramps up powerfully once you get to the Industrial and Modern eras, with a strong focus on production and commerce. Any UA bonus should not kick in until the Renaissance at the earliest (for hits and giggles, let's have two UAs, one called Speak Softly, the other A Big Stick). I'd keep the Minuteman, a so-so rifleman with scouting capabilities, and have an Assembly Plant or something as UB, a factory replacement giving a large boost to unit production in war time.
Aztec
Leader: Tlacaelel Cihuacoatl, because having another Montezuma is kinda boring
Gameplay: The Aztecs should be a warlike civ and should be comfortably at war for most of the game. Their unique stuff should facilitate this. They should have something like their Civ5 ability, like gaining culture or reducing war weariness with each enemy unit killed. For a UB I'd have a Telpochcalli which gives units a promotion that gains science points for each enemy unit killed, to help the Aztecs stay in the tech race. Note that they gain these bonuses from units killed, not experience. The Aztecs need to win their battles, 'cause otherwise they can't sacrifice captives and the world will end.
Chinese
Leader: Tang Taizong. I know he appeared in CivRev2 but that doesn't really count.
Gameplay: I think China should be the most versatile of all the civs, to reflect the multifacetedness of the civilisation, as well as the long history of political unity (meaning the capital - which in gameplay terms is you the player - gets to decide on a lot of things from very early on). A Chinese player should have ample resources to pursue any play style without having an innate advantage for any particular one. The UB could be a Yamen, a courthouse replacement that lets you choose which bonus it gives you. Cho-Ko-Nu makes a nice UU, though I'd prefer if it has a defensive bonus, because as China you might choose to pursue a more dovish style.
Egyptian
Leader: Amenhotep III
Gameplay: I always thought Persia's Civ5 bonus is a lot more fitting for Egypt, because of the running theme throughout Egyptian history of the bounty and stability provided by the Nile. So that's what I would have as a UA: longer golden ages. Their UB could be Workers Housing, which provides a bonus to building/wonder construction. War Chariot makes a great UU as it is.
English
Leader: Robert Walpole. Please, please, please?
Gameplay: The uniques should facilitate naval supremacy, easy overseas expansion, and making lots of gold through overseas trade... but only after the Medieval era. Your early game experience should be similar to the Americans': getting invaded a lot and no help from your uniques. Compared to the Yanks you should have a starting bias for islands so you should have an easier time, and your bonuses should kick in earlier, but the Americans ramps up more powerfully come the Industrial era. Also while the Americans can afford to be isolationist, you can't. Your wealth and prosperity will depend on ruling the waves and protecting your trade routes, but your uniques should help a lot with that. Ship of the Line makes a nice UU, perhaps Stock Exchange for UB. Settling overseas colonies should provide some sort of bonus or lower maintanance cost or something. Extra movement for naval units is pretty swell too.
French
Leader: Cardinal de Richelieu
Gameplay: France should be the China of European civs; strong, versatile, sort of jack-of-all-trades, but master of none. Also, Richelieu could be a very interesting leader to play in light of the revamped diplomacy system in Civ6; if you want to play a really scheming or underhanded kind of game, he could be your guy.
German
Leader: Konrad Adenauer
Gameplay: Let's avert the "warmongering German" trope this time and go for the "overworking German" trope. Make Germany a strong industrious/commercial civ that gets bonuses when dealing with city-states. I'd keep Panzer as UU because it's too iconic to lose, and also to screw with the German player who's been playing a peaceful trader all game; suddenly you have an uber-powerful offensive unit, and an economy strong enough to support lots of them. Do you give in to temptation and try a Weltoberung?
Greek
Leader: Themistocles. I'm so tempted to put here a Byzantine emperor, maybe Basil II, to avert the Byzantines being its own civ in a DLC. But fine, I'll pick someone from classical Athens.
Gameplay: I imagine Greece as like another England, except strong in the early game and weak in the late game. I'll have a UA that helps with research, and two UUs, a ship and a phalanx unit that's also amphibious.
Incan
Leader: Topa Inca Yupanqui
Gameplay: I want the Incas to provide a strong contrast to the Aztecs. Just as the Aztecs are the prototypical warmonger civ, the Incas should be the prototypical builder civ. From what we know geography is going to matter quite a bit more in Civ6, so let's exploit that. Make the Incas master of environments, because historically that's what they were. The Incan realm didn't just encompassed hills and mountains but also coasts and deserts and rainforests, and they built extensively in all. Also I'd have a slinger as a UU, which get a promotion allowing them to fight more effectively depending on where they were built (eg building one in a jungle city gives them bonuses in jungles)
Indian
Leader: Asoka. I know he appeared in Civ4 but hey he's not Gandhi. Also a nice figure to represent such a diverse and ancient civ, being someone who ruled long ago but used extensively by modern India as a unifying symbol.
Gameplay: Gonna annoy people by saying that India should be a pacifist civ that doesn't expand much territorially, but I also think that the "Population Growth" thing in Civ5 is dumb. An Indian player shouldn't be punished for expanding territorially but instead should be given incentives to expand non-militarily like through religion or commerce. Let's say a UA that gives bonuses for missionaries, and an improvement that you could build in city-state or other civs territories that contribute to your science or economy. Also War Elephants are lame UUs, can we have Mysorean Rockets instead.
Indonesian
Leader: Gajah Mada
Gameplay: A maritime trading civ that thrives on diversity. The Candi thing from Civ5 is genius, but is hampered a bit by how religion is treated in that game. If religion is more like how it was in Civ4, like a feature of the game environment that you can choose to grow and/or exploit as opposed to just an extension of a particular civ, that would be so much better. The special promotion thing for the Kris Swordsman is nice too, except nerf the base unit but let the player choose the bonuses (which should be geared towards defensive and amphibious ones). I think the Spice Islanders UA is meh, I'd actually replace it with something like Portugal's Civ5 UA, with resource diversity giving you a gold bonus.
Iroquoian
Leader: Ayenwatha
Gameplay: I must confess, I don't particularly like uniques that means a civ only excels in a particular environment. That doesn't mean that I don't think interacting with terrain and using it to your advantage should be a big part of the game, but the running theme of human civilisation is us adapting to new environments and changing existing ones and repurposing them for our own use. Now a UU or UB that gives you a terrain bonus is one thing but Civ5 all of the Iroquois' uniques encourage them to preserve forests. It's even problematic historically, as American Indians/Native Americans don't aim preserve forests, they manage them; management might means preserving forests sometimes, burning them other times. Instead the Iroquois UA or UB should play with the new Civ6 districts system to reflect how their concept of land care and ownership is radically different from the European conception. I'd keep the UU though.
Japanese
Leader: Ito Hirobumi
Gameplay: I really want Japan to be a maritime civ that's not particularly maritime, if you get my drift. An England with a strong land army, having a navy not so much to rule the waves as to get the land army to where it needs to go. So maybe having a bonus for Great Admirals instead of extra movement. The Samurai is too iconic not to have as a UU, and maybe a UB that helps cut unit support cost or something.
Korean
Leader: Myeongseong, not only because she's female, but since I've chosen Hirobumi for Japan, let's also have one of his most famous and determined opponent.
Gameplay: I want the three East Asian civs to provide a contrast to each other. So if China is the balanced civ, Japan is the warmongering civ, then Korea is the peaceful sciencey civ. And just as Japan is a maritime civ that's not particularly maritime, then Korea is a land-based civ that can more than hold its own at sea, so naturally Turtle Ship as the UU.
Malinese
Leader: Sundiata Keita
Gameplay: I'd like this to be a trading Civ that gains science from trade routes, with a fast medieval age cavalry to protect the caravans. We can repurpose the Mud Pyramid Mosque from Civ5 as UB and helps you gain extra culture or science with each trade route.
Mayan
Leader: Lady Xoc, a Mesoamerican female leader is a very fresh perspective don't you think?
Gameplay: So if the Aztecs are warriors, and Incans are builders, the Mayans are the mystics. Their unique stuff shouldn't give them any edge militarily but like India their means of expansions are through trade and religion. I actually wouldn't give them any UUs, but two UBs or an extra passive bonus. The Long Count thing in Civ5 is nice, I'd keep that.
Persian
Leader: I'm actually undecided on this. Cyrus or Darius are strong and safe but somewhat boring choices, I'm tempted to do with someone from the Sassanid era, especially since Extra History gave me a thing for Khosrow I, Troll of Trolls
Gameplay: I'd give them something like a Satrapies UA or UB that helps them consolidate their rule in conquered cities, allowing the Persians to conquer big and have an easier time maintaining their conquests than other civs. An Immortal UU very early in the game helps deal with barbs but too early to really be used effectively against other civs.
Roman
Leader: Marcus Aurelius
Gameplay: Rome should be the new Germany - the highly disciplined, highly militaristic, highly aggressive civ. Have the Legionary as a strong classical age UU, and have some sort of barracks replacement that gives a useful bonus well into the late game. Make roads cost less to maintain or something as well to help tie your conquests together.
Russian
Leader: Catherine
Gameplay: Russia should be big and hard to conquer. I'd introduce something like attrition into the game, and give Russia a General Winter UA making Russian territory inflict extra attrition, and reintroduce the Krepost UB or something similar so that borders expand more and faster.
Spanish
Leader: Isabella
Gameplay: Civ5 has the right idea with this civ so I'm not going to tweak much except to say that the bonus yield from natural wonders thing is weird. I'd probably replace it with better stuff from ancient ruins/goody huts except that might be a little OP.
Anyway, so that's how I'd select and design the civs. Tell us what you'd do and/or how I'm wrong and an idiot.
Also I'm gonna try to nominate leaders who haven't appeared in Civ before. And I set myself an arbitrary quota of 20% female leaders.
Also I spent like three hours of serious thought on this, so please let me have it as its own thread. This isn't a "what civ you'd like to see" thread, this is a "which civs would you choose and what sort of play style you'd design them for and why" thread.
Here goes:
American
Leader: Theodore Roosevelt, as the guy most responsible for turning the United States into a Great Power, and fits quite well with my intended theme for the civ (see below)
Gameplay: It should be a challenging civ to play in the early game, but ramps up powerfully once you get to the Industrial and Modern eras, with a strong focus on production and commerce. Any UA bonus should not kick in until the Renaissance at the earliest (for hits and giggles, let's have two UAs, one called Speak Softly, the other A Big Stick). I'd keep the Minuteman, a so-so rifleman with scouting capabilities, and have an Assembly Plant or something as UB, a factory replacement giving a large boost to unit production in war time.
Aztec
Leader: Tlacaelel Cihuacoatl, because having another Montezuma is kinda boring
Gameplay: The Aztecs should be a warlike civ and should be comfortably at war for most of the game. Their unique stuff should facilitate this. They should have something like their Civ5 ability, like gaining culture or reducing war weariness with each enemy unit killed. For a UB I'd have a Telpochcalli which gives units a promotion that gains science points for each enemy unit killed, to help the Aztecs stay in the tech race. Note that they gain these bonuses from units killed, not experience. The Aztecs need to win their battles, 'cause otherwise they can't sacrifice captives and the world will end.
Chinese
Leader: Tang Taizong. I know he appeared in CivRev2 but that doesn't really count.
Gameplay: I think China should be the most versatile of all the civs, to reflect the multifacetedness of the civilisation, as well as the long history of political unity (meaning the capital - which in gameplay terms is you the player - gets to decide on a lot of things from very early on). A Chinese player should have ample resources to pursue any play style without having an innate advantage for any particular one. The UB could be a Yamen, a courthouse replacement that lets you choose which bonus it gives you. Cho-Ko-Nu makes a nice UU, though I'd prefer if it has a defensive bonus, because as China you might choose to pursue a more dovish style.
Egyptian
Leader: Amenhotep III
Gameplay: I always thought Persia's Civ5 bonus is a lot more fitting for Egypt, because of the running theme throughout Egyptian history of the bounty and stability provided by the Nile. So that's what I would have as a UA: longer golden ages. Their UB could be Workers Housing, which provides a bonus to building/wonder construction. War Chariot makes a great UU as it is.
English
Leader: Robert Walpole. Please, please, please?
Gameplay: The uniques should facilitate naval supremacy, easy overseas expansion, and making lots of gold through overseas trade... but only after the Medieval era. Your early game experience should be similar to the Americans': getting invaded a lot and no help from your uniques. Compared to the Yanks you should have a starting bias for islands so you should have an easier time, and your bonuses should kick in earlier, but the Americans ramps up more powerfully come the Industrial era. Also while the Americans can afford to be isolationist, you can't. Your wealth and prosperity will depend on ruling the waves and protecting your trade routes, but your uniques should help a lot with that. Ship of the Line makes a nice UU, perhaps Stock Exchange for UB. Settling overseas colonies should provide some sort of bonus or lower maintanance cost or something. Extra movement for naval units is pretty swell too.
French
Leader: Cardinal de Richelieu
Gameplay: France should be the China of European civs; strong, versatile, sort of jack-of-all-trades, but master of none. Also, Richelieu could be a very interesting leader to play in light of the revamped diplomacy system in Civ6; if you want to play a really scheming or underhanded kind of game, he could be your guy.
German
Leader: Konrad Adenauer
Gameplay: Let's avert the "warmongering German" trope this time and go for the "overworking German" trope. Make Germany a strong industrious/commercial civ that gets bonuses when dealing with city-states. I'd keep Panzer as UU because it's too iconic to lose, and also to screw with the German player who's been playing a peaceful trader all game; suddenly you have an uber-powerful offensive unit, and an economy strong enough to support lots of them. Do you give in to temptation and try a Weltoberung?
Greek
Leader: Themistocles. I'm so tempted to put here a Byzantine emperor, maybe Basil II, to avert the Byzantines being its own civ in a DLC. But fine, I'll pick someone from classical Athens.
Gameplay: I imagine Greece as like another England, except strong in the early game and weak in the late game. I'll have a UA that helps with research, and two UUs, a ship and a phalanx unit that's also amphibious.
Incan
Leader: Topa Inca Yupanqui
Gameplay: I want the Incas to provide a strong contrast to the Aztecs. Just as the Aztecs are the prototypical warmonger civ, the Incas should be the prototypical builder civ. From what we know geography is going to matter quite a bit more in Civ6, so let's exploit that. Make the Incas master of environments, because historically that's what they were. The Incan realm didn't just encompassed hills and mountains but also coasts and deserts and rainforests, and they built extensively in all. Also I'd have a slinger as a UU, which get a promotion allowing them to fight more effectively depending on where they were built (eg building one in a jungle city gives them bonuses in jungles)
Indian
Leader: Asoka. I know he appeared in Civ4 but hey he's not Gandhi. Also a nice figure to represent such a diverse and ancient civ, being someone who ruled long ago but used extensively by modern India as a unifying symbol.
Gameplay: Gonna annoy people by saying that India should be a pacifist civ that doesn't expand much territorially, but I also think that the "Population Growth" thing in Civ5 is dumb. An Indian player shouldn't be punished for expanding territorially but instead should be given incentives to expand non-militarily like through religion or commerce. Let's say a UA that gives bonuses for missionaries, and an improvement that you could build in city-state or other civs territories that contribute to your science or economy. Also War Elephants are lame UUs, can we have Mysorean Rockets instead.
Indonesian
Leader: Gajah Mada
Gameplay: A maritime trading civ that thrives on diversity. The Candi thing from Civ5 is genius, but is hampered a bit by how religion is treated in that game. If religion is more like how it was in Civ4, like a feature of the game environment that you can choose to grow and/or exploit as opposed to just an extension of a particular civ, that would be so much better. The special promotion thing for the Kris Swordsman is nice too, except nerf the base unit but let the player choose the bonuses (which should be geared towards defensive and amphibious ones). I think the Spice Islanders UA is meh, I'd actually replace it with something like Portugal's Civ5 UA, with resource diversity giving you a gold bonus.
Iroquoian
Leader: Ayenwatha
Gameplay: I must confess, I don't particularly like uniques that means a civ only excels in a particular environment. That doesn't mean that I don't think interacting with terrain and using it to your advantage should be a big part of the game, but the running theme of human civilisation is us adapting to new environments and changing existing ones and repurposing them for our own use. Now a UU or UB that gives you a terrain bonus is one thing but Civ5 all of the Iroquois' uniques encourage them to preserve forests. It's even problematic historically, as American Indians/Native Americans don't aim preserve forests, they manage them; management might means preserving forests sometimes, burning them other times. Instead the Iroquois UA or UB should play with the new Civ6 districts system to reflect how their concept of land care and ownership is radically different from the European conception. I'd keep the UU though.
Japanese
Leader: Ito Hirobumi
Gameplay: I really want Japan to be a maritime civ that's not particularly maritime, if you get my drift. An England with a strong land army, having a navy not so much to rule the waves as to get the land army to where it needs to go. So maybe having a bonus for Great Admirals instead of extra movement. The Samurai is too iconic not to have as a UU, and maybe a UB that helps cut unit support cost or something.
Korean
Leader: Myeongseong, not only because she's female, but since I've chosen Hirobumi for Japan, let's also have one of his most famous and determined opponent.
Gameplay: I want the three East Asian civs to provide a contrast to each other. So if China is the balanced civ, Japan is the warmongering civ, then Korea is the peaceful sciencey civ. And just as Japan is a maritime civ that's not particularly maritime, then Korea is a land-based civ that can more than hold its own at sea, so naturally Turtle Ship as the UU.
Malinese
Leader: Sundiata Keita
Gameplay: I'd like this to be a trading Civ that gains science from trade routes, with a fast medieval age cavalry to protect the caravans. We can repurpose the Mud Pyramid Mosque from Civ5 as UB and helps you gain extra culture or science with each trade route.
Mayan
Leader: Lady Xoc, a Mesoamerican female leader is a very fresh perspective don't you think?
Gameplay: So if the Aztecs are warriors, and Incans are builders, the Mayans are the mystics. Their unique stuff shouldn't give them any edge militarily but like India their means of expansions are through trade and religion. I actually wouldn't give them any UUs, but two UBs or an extra passive bonus. The Long Count thing in Civ5 is nice, I'd keep that.
Persian
Leader: I'm actually undecided on this. Cyrus or Darius are strong and safe but somewhat boring choices, I'm tempted to do with someone from the Sassanid era, especially since Extra History gave me a thing for Khosrow I, Troll of Trolls
Gameplay: I'd give them something like a Satrapies UA or UB that helps them consolidate their rule in conquered cities, allowing the Persians to conquer big and have an easier time maintaining their conquests than other civs. An Immortal UU very early in the game helps deal with barbs but too early to really be used effectively against other civs.
Roman
Leader: Marcus Aurelius
Gameplay: Rome should be the new Germany - the highly disciplined, highly militaristic, highly aggressive civ. Have the Legionary as a strong classical age UU, and have some sort of barracks replacement that gives a useful bonus well into the late game. Make roads cost less to maintain or something as well to help tie your conquests together.
Russian
Leader: Catherine
Gameplay: Russia should be big and hard to conquer. I'd introduce something like attrition into the game, and give Russia a General Winter UA making Russian territory inflict extra attrition, and reintroduce the Krepost UB or something similar so that borders expand more and faster.
Spanish
Leader: Isabella
Gameplay: Civ5 has the right idea with this civ so I'm not going to tweak much except to say that the bonus yield from natural wonders thing is weird. I'd probably replace it with better stuff from ancient ruins/goody huts except that might be a little OP.
Anyway, so that's how I'd select and design the civs. Tell us what you'd do and/or how I'm wrong and an idiot.