I've now hit the end of the content (I think) and so I'll list some areas of that I hope you'll improve in future versions below. The art is very good, and I like the idea of a kingdom management game, so kudos for what you've made so far. I preface this just because it will seem very negative in isolation for me to just point out 30 things I don't like, but I'm only doing this because I do like it overall and I understand it will be in development for a while.
Splitting the three types of kingdom management across 3 different menus each associated with a portrait of a vassal character is not great. I would probably keep the cutscenes where you unlock each type of management from each person, but have them just unlock new areas on a single, unified management screen. I think there's enough space for everything you need in the game on a single screen, assuming you can click each city to swap out which one you're working on / analysing tribute from. You can put a little portrait of each person next to each section of the page if you want to keep the flavour of it being managed by a specific person.
Needing to go to the field to unlock dancers is probably not great since you can miss that. I assume you either once planned, or still plan to add more to the field, because it's just an empty place with that one thing that so far.
The relationship between kingdom population and resource output via tribute versus from town upgrades is unclear. Does population boost how much they give you, or is it only a resource designed for giving you slaves? It seems to drain food based on population, and each city has it's own food supply separately. Do I automatically get the surplus in my armies when they hit the cap, or only if I demand tribute? Is it better if I want to farm a city to have a cap of 50 population so they don't eat too much? At minimum I would want net/loss statistics on food and other resources to help make informed decisions and see the impact of selecting different tribute types.
For simplicity, a more radical suggestion is to not actually track population or food requirements for each city. Instead, the city could be expressed in terms of how many resources of each type it outputs - and you'd upgrade it to improve that. A newly conquered city could give a pittance, then you do a "repair city" upgrade to represent bringing it back into order, then start building out new farms or mines to really make them productive.
If you want to make logistics and management more complex instead that's also fine, but ofc you will make the design and balancing a lot more challenging.
The battle system seems a little superfluous when there's only one person who raids you when threat is too high so it really only triggers once or maybe twice per game. I will say it's annoying that the attack happens sometimes (actually often) straight after a raid so you have no soldiers to deal with that. If they're responding to the threat of my own raids, why did their army get to my capital before my army returned home? I mean obviously it's a game and I assume you're trying to incentivise keeping a defence, but it's overall quite wonky right now.
In terms of minor UI friction - the logic you have for speeding up the number increase/decrease for soldiers button is a little annoying and I'd prefer more specific control for adding 5 or 10 or 50 or whatever. There's a problem training dancers when you have like 400 guys and you struggle to pick less than 20 dancers to train because the same control logic is used there - if you have hundreds and hundreds, a single tap or click seems to zoom the numbers a lot in either direction, so you struggle to hit the exact amount you want. I'd also like to see total available soldiers on the screens where I select how many soldiers to use. Yes you can find out by hitting the max, but if you have say 80 soldiers it takes a long time to click that high.
The brainwashing screen has some reactivity I like (the expressions, the little dialogue comments) but when you cross 2 thresholds quickly, as you often do because it's not a very slow process, you often have to wait idk 6 to 10 seconds for one comment to fade out then the other to fade in. Perhaps one can stack on top of the other since there's a lot of space on screen, just so that happens faster.
Much like a lot of things, the brainwashing is pretty easy once you understand the rules. I remember the first time I played a much earlier version of this, I was very confused how it worked with the bubbles - I still think it's maybe a little unintuitive to someone who isn't sure what they're doing just seeing that screen for the first time. I don't have specific suggestions there to improve that.
There's a game flow issue with the threat attack lady. When you interrogate her you only have limited tools, and then after you beat her you get told you have more tools now. But if you have already brainwashed the 3rd kingdom person, you just have the new tools with no explanation. There's nothing stopping you from managing your threat properly to avoid getting attacked prior, so you don't get a tutorial on those or anything.
Oh and if energy is limited on those screens, I should be able to see what my energy is! Sometimes I get randomly told I'm exhausted but like, I can't see whether I will be until it randomly happens.
