Terrain: The land hexes being at various levels is AWSOME, yet hard to see sometimes.  Really sucks moving a unit right up to a hex to attack, and only then finding out after that you can't do that!  Could you please implement a red hex border system to make it easy to see which hexes do NOT connect.  Maybe just as an option that can be turned on that only turns on when you have a unit selected.

Ages: I mostly love how these work, but it always feels like I'm just starting to get the feel of the culture, and I hit the 7 stars.  I've tried sticking with them as far as 20 stars, but still only just usually getting the unit, and it's on to the next one, only NOW making the last one's units!  Maybe up this to 5 stars in each category and double the stars needed to 14.  This would probably need a big expansion of techs and socials also, as well for making a longer game, but it's a civ game, that's fine.  It's not like I'm ever finishing one game in a sitting or five anyway.

Ages Gameplay Differences: Really only the Neolithic age feels different.  I'd love this to be more Spore-like, where each age felt like a different game almost.  The boats for most of the game can't leave the coast for safety, so maybe the Neolithic tribe units should have the same thing, not being more than 2 spaces or more than one region from each other or a village, so that they have that limited exploration mechanic.  Or better yet, make the neolithic map just one region that you zoom out from, shrinking it six times the size once you get to the Ancient age!  The Ancient age could be more exploring the continent, and instead of training an army, you train military campaigns, which take much longer, and are one-shots, leading to a one-turn war using a collection of units you could train.  The Classical age would be the first one you actually start training standing armies, but like cities, you should also be limited in how many you can support, and how far from your lands it can go.  In real history even up to WWI, they starve if not supplied regularly.  

Techs/Socials: I like them, but they both feel very small.  Would love to see these at least double in size.

Events: These are GREAT!  Why isn't there at least one or more of these very turn!  Would really make the experience much more storied.  Each should have a smaller impact on the game, but make more of these!  I'd love hundreds of random story events so you never know what fate will throw at you!  No matter how good a leader you are, fighting fate is the hardest thing.  Maybe add rumors notes occasionally to things that happen near the edge of your fog-of-war vision like "Reports of an army moving near here" or "scouts say plentiful/desolate ocean/mountain/desert/forest lies past here"

Diplomacy/Resolving wars: I have no clue how to conquer someone!  I crush every city and army, yet can only demand they become a vassal or give me one territory, yet because of the names, I have no clue which one is which, since you can't see their names!  Operating peacefully is great, and works great.  I like the trading of resources, and all the various policies to get along with people, but war is needlessly stupid to figure out.  I like the war exhaustion.  But why can't I just wipe someone out, as was quite common historically?  I should be able to just raze their cities if I can't just make them mine.

Map options: It's impossible to see which resources you are gathering, and which ones you aren't, as the map button just turns them all on/off.  Also as previously mentioned, the area names are not ever visible.  Maybe add a few more map views.  I love how things get named when you zoom out and wish I could turn this on while zoomed in, turning off all the city and unit flags.  I'd love the religion, society, and everything else like this all centralized in one spot you can cycle through lots of different map overlays.

Technical issues: Lots of little issues with graphics getting stuck on the screen like battle previews just staying on the screen indefinitely, or the travel paths being ridiculously long for going a single space because it got confused.  Also, it's much more clunky and slow in processing moves, none of which I recall happening in the Lucy Opendev.  Hopefully, these were just errors in implementing new code and will be fixed in the future.

Quarters

Artisans Quarter should be treated as a quarter (being able to build quarters around it without a nearby quarter from a main plaza or administrative center.

Should be able to freely place Quarters within Territories to create good adjacency clusters. It would also enable to build Quarters on islands.

Emblematic Harbor Quarters (Cothon, Haven...) doesn't disallow building Harbors when changing Era and Culture. It could be to advantageous to build multiple Harbors. However, it might be allowable to have multiple Harbors for multicostal Territories.

Territories

The Territory system is a great idea. It justifies and incentivizes map painting (for Expansionist Stars), also, it won't be necessary to build a City or attach a territory to gain access to the Strategic and Luxury resources.

Revealing Strategic resources locations right at the beginning of the game is a great idea (and a nice jab to Civilization 6), as it won't ruin District- sorry, Quarter planification when preparing for adjacency.

Combat

Units move too slowly. Add an option to make them move faster. Also enable to build siege weapons in cities.

Religion

Quite generic, maybe add some gameplay changing tenets like Holy War (generate extra war support against empires of a different religion).

Stability

The Stability tab gets too tall as the game goes on for smaller window sizes. Instead, only show the total values for positive and negative Stability, then add a sublist for the details when hovering on the positive or negative values.

Independent people

They act both like cities states (if peaceful) or barbarians clans (if aggressive) in Civilization. It could interesting to add more diplomatic options when interacting with them (like protectorates, buffers, colonies...) for various diplomatic benefits and opportunities.

Civics

Not being able to change Civics (except in very specific circumstances), might be too constraining. What if a religious player goes irreligious by accident? Changing Civics doesn't have to be free, but should be possible in case of a bad choice, or change of strategy.