The game is very clearly unfinished. Some of the designs are mind bogglingly strange, and probably would work except they feel cobbled together - a symptom of an unfinished game. These other things in the game are also symptoms of an unfinished game:
* UI is horribly polished. I am talking arrows not being centered, low res, etc.
* Lack of QoL that anyone who play for a few hours can point out. Not fixed because they are low priority and Firaxis clearly ran out of time. The game doesn't explain at least half of the mechanics that are going on. Bonuses you picked on age transition is not referenced anywhere so I hope you wrote them down.
* Civs are limited. Part of the problem is the 3-age system, but also mainstay civs like Great Britain are not even present in the base game.
* Mechanics from one age just don't even translate into the next age. That probably would be fine except the entire age transition is abrupt. Clearly needed more time to bake.
* 20% of the "leaders" are personas (e.g., this variation fo Napoleon). They ran out of time to develop new leaders and so just did this to increase the number.
* The game clearly has a 4th age. You can tell the 3rd age still has a summary score with points meant to go into the 4th age. Cut short due to the game running out of time.
* Independent powers just disappear between age transitions. New ones show up. Feels really jarring. Why? Probably ran out of time to build the right thing.
* Diplomatic Victory doesn't exist, despite building a new Diplomacy system. Probably because it's meant for the 4th age with the UN, since the 3rd age ends around 1960s.
* Map generation is so, so terrible. Most map types from what one would expect from Civilization is gone. Bet they ran out of time here. You also can't play with more than 8 total civs.

They then quickly announced DLCs to add civs and pretty sure they'll "fix" things with expansions, like adding the 4th age and fixing the age transition.

There are also really bad design decisions:
* You're railroaded into winning the game through one of few ways. Gone are the days where you can do many different things to achieve say Cultural Victory, and some civs have novel ways to generate the inputs to do any of those methods (e.g., Aztecs get Culture Points from killing units). No, cultural victory works this way for everyone. Bonus points, the Culture you generate isn't the main input for it. What?
* Very strange Euro-centric views on how each age is "supposed to go" as victory conditions. For example, it doesn't matter if you're Ming China or the Incans, your goal in the Exploration Age is to explore new lands and colonize like the few European countries that did so in real history.
* AI is awful. Mainstay of Civ at this point, but all the same bugs and annoyances from previous games that were fixed by DLCs and expansions are back.

For whoever is interested in this game, I suggest playing Civ 6 which is a more complete game for a much lower price until they fix this. Do not feed into this predatory practice of launching a beta of a game full of bugs and unfinished mechanics, then pay more to buy DLCs and fixes to get an actual complete product. This game is probably not worth the time and money right now.

I will say I am having fun. I played 3 full games. I can see the game being fun after 1-2 more years. I do regret buying this on release. I should have waited.

The game is very clearly unfinished. Some of the designs are mind bogglingly strange, and probably would work except they feel cobbled together - a symptom of an unfinished game. These other things in the game are also symptoms of an unfinished game: * UI is horribly polished. I am talking arrows not being centered, low res, etc. * Lack of QoL that anyone who play for a few hours can point out. Not fixed because they are low priority and Firaxis clearly ran out of time. The game doesn't explain at least half of the mechanics that are going on. Bonuses you picked on age transition is not referenced anywhere so I hope you wrote them down. * Civs are limited. Part of the problem is the 3-age system, but also mainstay civs like Great Britain are not even present in the base game. * Mechanics from one age just don't even translate into the next age. That probably would be fine except the entire age transition is abrupt. Clearly needed more time to bake. * 20% of the "leaders" are personas (e.g., this variation fo Napoleon). They ran out of time to develop new leaders and so just did this to increase the number. * The game clearly has a 4th age. You can tell the 3rd age still has a summary score with points meant to go into the 4th age. Cut short due to the game running out of time. * Independent powers just disappear between age transitions. New ones show up. Feels really jarring. Why? Probably ran out of time to build the right thing. * Diplomatic Victory doesn't exist, despite building a new Diplomacy system. Probably because it's meant for the 4th age with the UN, since the 3rd age ends around 1960s. * Map generation is so, so terrible. Most map types from what one would expect from Civilization is gone. Bet they ran out of time here. You also can't play with more than 8 total civs. They then quickly announced DLCs to add civs and pretty sure they'll "fix" things with expansions, like adding the 4th age and fixing the age transition. There are also really bad design decisions: * You're railroaded into winning the game through one of few ways. Gone are the days where you can do many different things to achieve say Cultural Victory, and some civs have novel ways to generate the inputs to do any of those methods (e.g., Aztecs get Culture Points from killing units). No, cultural victory works this way for everyone. Bonus points, the Culture you generate isn't the main input for it. What? * Very strange Euro-centric views on how each age is "supposed to go" as victory conditions. For example, it doesn't matter if you're Ming China or the Incans, your goal in the Exploration Age is to explore new lands and colonize like the few European countries that did so in real history. * AI is awful. Mainstay of Civ at this point, but all the same bugs and annoyances from previous games that were fixed by DLCs and expansions are back. For whoever is interested in this game, I suggest playing Civ 6 which is a more complete game for a much lower price until they fix this. Do not feed into this predatory practice of launching a beta of a game full of bugs and unfinished mechanics, then pay more to buy DLCs and fixes to get an actual complete product. This game is probably not worth the time and money right now. I will say I am having fun. I played 3 full games. I can see the game being fun after 1-2 more years. I do regret buying this on release. I should have waited.