After some 50 hours in all three OpenDevs combined, I’ve gathered some thoughts. Loved the game so far. Apologies for the Great wall of text. I tried to be as concise as possible. 

Balance

• Horde units are OP. No getting around it. The cost to spawn a new unit into the army needs to be higher. I would also disable food yields from killed units (cannibalism?) and limit it to ransacking and hunting. As for the ability to attack twice, either reduce the unit’s strength or only allow movement after one attack. 
• Hanging gardens feels inferior to other ancient wonders. It’s just a slightly boosted artisans’ quarter?
• Some of the ideological axis felt imbalanced – production and science are way more useful than an equivalent amount of money or influence.
• The amount of curiosities in the Neolithic is so high it takes away from the joy of finding them. I think their respawn rates in particular need to be toned down. 
• Overall the game feels very easy. AI is passive militarily and progresses quite slowly. Also, their cities seem to suck. They often spam useless, terribly placed districts and never have any population. Where do they lose their population when their armies are so small?

Cities

• Cities need at least a semi-hard cap on districts. In this iteration things just get out of hand. To add to the possible solutions, I suggest a soft cap based on eras, instead of population. (Population is just too easy to come by in the Neolithic, as you can come into the Ancient era with dozens of scout units ready to disband into your cities.) When the city is above the limit, a noticeable stability hit is applied so that stability gameplay stays relevant. The stability drop really needs to sting, but when it is clearly communicated through UI it becomes an interesting choice for the player. Currently you barely notice stability in the cities as it is too easy to maintain. 
• Market quarters feel useless. I barely ever built them, yet still managed to hoard massive amounts of money. Maybe add more adjacency bonuses to them?
• Infrastructure felt too lightweight from gameplay standpoint. You can just spam them at a rather low cost without a worry. There’s very little decision-making process required to which infra you should build. I’d love a maintenance cost or something. 
• It’d be handy to be able to queue up multiple ceremonies of the same type when there isn’t anything else to build
• Deconstructing districts would be a useful ability for city planning. 

Visuals

• Allow rotation of camera – the amazing graphics deserve to be viewed from all angles. 
• Placing multiple emblematic districts in a city starts looking too repetitive too fast. If adding different variations of emblematic districts is too much asked, at least allow to rotate them. 
• Ability to rotate wonders would as well be much appreciated. 
• When zoomed out, the political world map would be much more readable if each territory was filled with the colour of the respective empire instead of just grey interiors with coloured borders. Territories under occupation could be striped in the colours of the invader. 
•  I’d also love to be able to zoom out without the map shifting into the simplistic grey mode, and rather retain the natural landscape. Don’t know if this is possible performance-wise though. 
• The pyramids’ golden top part sometimes has a shade on the wrong side: Left side of the pyramid would be in shade while the left side of the top is lit and vice versa. Applies to both Giza and the Egyptian quarter.
• I feel like the administrative centre styles of later eras don’t get enough visibility with most of the cities featuring ancient or classical buildings. A solution would be a city project that upgrades the administrative centre to that of the current culture. 
• Not sure if status related, but there was an excessive smog effect on my city towards the end that I didn’t like. Maybe limit it to production quarters? I don’t want dust on my wonders.
• Ships seemed to lack any wake effect when moving on waters. Would be nice

UI

• Any chance for a minimap? I appreciate the length we can go to with zooming out, but it still doesn’t show the entire world at once. 
• Information on the transport vessels is needed when embarking units! Player needs to know what kind of a vessel is embarked; what is its strength, and can it traverse deep waters?
• The ability to turn off the grey battle area is great! It would, however, be helpful if the outer borders of the area could still be toggled visible to know where they are. 
• Also, when moving units outside of a battle, it is unclear where they cannot move due to a battle. Solution would be to highlight the borders constantly or when hovering over inaccessible area. 
• Army panel’s unit icons are too big and get in the way of each other. Particularly troublesome when selecting individual units in an army bigger than 4. 
• I love being able to turn off UI! Just add the ability to turn off borders as well and its perfect.
• The civics panel needs to be viewable simultaneously with events as I would want to see where I stand on the ideological axis when I’m making decisions. Currently you have switch between the two and try to remember which ideologies are in question. 
• During the era change cutscene one moves their mouse out of the way to the edge of the screen. When the architecture change camera pan comes, the mouse on the edge of the screen throws the camera off. So prevent that somehow 
• The actual deed could be highlighted somehow in the “World deed accomplished” notification, to more easily spot it among the text. 
• “The era star achieved notification” should inform on which type of an era star was achieved. 
• More icons are needed for different units. It’s very confusing when pikemen and scouts have the same icon and crossbowmen look like riflemen.
• The era star categories must not move around in the empire screen. Makes it ever more difficult to track what you’re supposed to achieve.
• When placing a wonder, the resulting FIMS yields should be displayed like when placing a district.
• In the cultures screen, when hovering over the affinity icon it wouldn’t display any tooltip on the abilities, which would be very useful.
• It is unclear what is the exact final sum of stability in a city. 
• City info needs a number of all the territories it consists of. Couldn’t find one
• Other civs degrading treaties with me was not notified properly if at all. 
• During battles it seemed hard to find out which independent people was attacking you. The name was properly hidden
• The competitive deeds list would benefit from grouping by type. Colour coding?
• The diplo screen should have a history of a civilization in the same fashion with the relation history. I want to know who they were prior to their current culture. 
• Badges tooltips still unfinished? More info def. needed.
• A notification should be minimized in the bottom bar also when I press the spyglass instead of the “Acknowledge”.
• Income tooltip should specify which vassal a certain income is coming from. 
• Atheism civic should more clearly explain what kind of changes it entails. 
• It was a bit too unclear which wonders were holy sites. 
• Sometimes when placing a district, it would not show which yields would be lost. I want to stress that it’s very important to get this working flawlessly to support an already confusing exploitation system.
• The diplo screen didn’t tell me how much of war desire do I exactly need to declare a war
• “Show unclaimed wonders” button is inaccurate as it also shows claimed wonders : )

Terrain

• While the natural wonders look amazing, I do miss the more unique benefits they give in that other game. In this state they felt bland.
• Will there be proper deserts of sand? Not just prairie or stone fields

Battles

• While I also commend this suggestion by u/BrunoCPaula, the biggest gripe I have with battles is the amount of movement – I’d reduce it to make each tile moved feel more important strategically. Currently there is too much running around. This can be achieved by reducing movement points across the board or increasing movement cost of difficult terrain. Regarding the latter, I observed that forests for example didn’t slow units down despite the movement cost of 2. I would increase it to 3 really. For example, rocky fields and arctic tiles could use an increase in cost too. Also, enemy units should limit movement by their adjacency in Zone of control fashion.
• I also feel most ranged units have too much range.
• When in battle, accidentally clicking on a mountain tile closed the battle view. Quite annoying
• It’s too easy to forget autosolving of battles on and suffer of the consequences. Give an option to autosolve once or to leave it on.
• Units’ lines of sights feel unintuitive sometimes. To better educate players in their logic, highlight the tile that’s blocking the LOS when hovering over a target unit.
• Battles automatically suck in all the surrounding units. Sometimes I wanted to exclude a unit from joining a battle
• Then again, sometimes I had trouble with some reinforcements not joining a battle. This seemed to happen particularly in sieges.  
• Cavalry charge ability didn’t seem to work?
• In the beginning it felt a bit unclear when the enemy skipped their turn. Got used to it, but new players would benefit from clarity. 
• Disabling any optimized, automated placement of units in the beginning of deployment phase would more actively force the player to look for the best tiles to deploy on. Currently a bit too much handholding. 

Miscellaneous 

• Units need a true sleep button from which they never wake up. Sentries wake up to every neutral unit.
• I’d love to see culturally appropriate hats on the avatars. Don’t know if it’s difficult to implement
• Diplomatic decisions could affect the negotiators’ ideological axis. For example, scientific agreement takes you toward progress, refusing to cooperate toward homeland, and cooperation toward world.
• The auto-explore mechanic disregards deep seas causing surprising deaths by drowning.
• A bug occurred during some late game sieges, when the siege control panel didn’t show at all, not letting me abandon, assault or maintain the siege. Just stuck for the rest of the game.
• Manually moving an auto-exploring unit should disable the auto-explore.
• When detaching a unit from an army it’d be more fluent if the selection followed into the detached unit instead of remaining in the source army. Too many times I detached a unit and then accidentally moved the bigger army. 

Points of confusion

• Didn’t seem able to negotiate open borders with a civ that’s a vassal under another civ. Not even by talking to their liege.
• How do I place a luxury manufactory in a later era when all the deposits already have an artisans’ quarter? 
• When choosing a culture, the text “Unlocks action Buyout on Empire” seemed pointless. Isn’t it always unlocked anyway?
• Barbican seemed pretty useless. Not even the city watch infrastructure carries over to it?
• I seemed to get the defending bonus while attacking in a battle I initiated. 
• I found it weird that I was rewarded for declaring a surprise war with a badge that’s beneficial to me. 

I agree with all the things that Rymy is saying. She/he has done a great job in her/his post. I would like to extend her/his feedback with mine.

Units: Like Rymy says the Horde Unit cannot have the double attack. Other special units have not that great advantage. For balancing either give every special unit such a great bonus or nobody.

Cities: I think resources have some priority at the current state of the game: 1.Production 2. Food 3. Influence/Stability (Early or Mid Game) 4. Science (just getting enoug all along or the AI is very bad with it) 5. Faith (the religion game is too minor) 6. Money (i don't know where i get it but I get enourmous sums plus Market districts get no good adjacency bonus). Production is too big in this game. The same problem like in another game where a "production" district is strategically mandatory. Because of Science and production and too much money there is no great stability problem in transferring all outpost into cities. There must be some kind of revolting mechanic, something really bad happening to you if you overextend in city creation.

Speed: I think the game has something really great going with this ages but it must feel like ages. So I would be grateful for a game with slower pace. At the moment I need something like 20 rounds for each age and that is too quick. I'm just trying hard to get the benefit out of each age because the next age is coming so early.

Map: The map should be greater or with less civs because you want to feel the great journeys on earth in the neolithic age. Because of the inbalance of size and number of civs it is more a run for outposts. The main point is getting food for spreading and influence for planting outposts. I would like that you can only put down one outpost in the neolithic age which becomes your main city. This would make it more important to settle down or to get more scout units before transferring.