i'll make my case using only gameplay, as well as a select 'few' ideas.
SOTE has maps bigger than anything in CIV so far. and it was made by two people
instant build 99% of units and buildings
it doesn't take 100 years to equip 1 spearman. allow the player to raise batches of units at once to then engage in war with enemies. then the game will enter war time and everything will slow down.
civilizations are bundles of traits on a spectrum from one another.have premade bundles. bundles can also appear mid game. civ languages, if custom, are ai generated using GPT-4. with entire language families that can spread.
extremely customizable worldviews
every civ has a worldview that can be spread to enable more players to swap to other civilizations in time or protected to ensure your national identity. worldviews encompass both philosophy and religion. player customizes worldview. worldviews are extremely customizable.
separation of civ from state, 'you will fail'
separate the civilization from the state so when the state is destroyed the player can keep going, or even go to a rump state related to their civilization. the expectation built in is that no empire is eternal, but civilizations can be. chinese states came and went, but the civilization stood tall and proud. the challenge for civ players should not be 'Can I keep this state going' but 'can I keep my civilization going no matter how altered it gets even if I get taken over or fracture into a thousand states or revert into hunter gathering?'
players can swap between states in civilizations at will with a cooldown.
some players come after others
in real life, despite the fact germans became settled MUCH later than the Egyptians or Chinese, they were still important on a regional and later global level. there should be rules to determine how early a state forms.
non linear tech trees
the player should decide how technological advance looks like in their world. want to have the world's best fortifications but terrible agriculture? go ahead. do so.
every tile has people
80-90% of the world's population was rural for 90% of human history. population should have REAL numbers so you can see number go up.
geography should highly affect gameplay
geography is highly influential in the workings of human civilization, and second to that are the ideas themselves. if we can account for how geography affects state formation, the diffusion of culture, and so on, this means that every single game will be wildly different and immersive.
let's see how this fulfills all 4 xs of the 4x genre
explore: different players will explore differently. you can also 'explore' your culture by building onto it more.
expand: expand your civilization, or choose a state in the civilization to expand
exploit: exploit the resources you find and your allies or enemies
exterminate: exterminate yourself and change your civilization, exterminate other states belonging to other civilizations, etc
you could have games like where the Japanese appear as an emergent civ that forms when they fulfill the conditions of state generation, and then proceed to fight off an invasion by their imperial neighbor. The Japanese could then settle a new continent and form a new civilization from the intermingling of their culture and the native's culture.
you could have games where the indo europeans settle next to the Malians and trade with them, eventually merging their two civilizations together
you could have games of vast conquest bigger than what Alexander did in around 15 years. let's say the Polish somehow form a state. and then begin to interact with the countless Mesopotamian states nearby. one day a young Polish Noble with money, talent, and ambition gathers sixty thousand men to conquer the ends of the world with. He has many children and ends up forging an empire reaching over 4 million square kilometers, spreading Polish philosophy and culture everywhere.