Big Thanks for all the suggestions!
Some are really good and I'll try to implement them somehow. For example, combining multiple game modes is an idea I've had for a while too - I just need to adjust the UI as it's currently just a drop-down.
Some of these suggestions need more thought on my side, for example, if I can find a clever way to better distinguish cavalry from horse archers.
Some suggestions are also too big to implement, like unique civilizations. I see you got a lot of ideas from the civilization games. I have the idea of adding more biomes to the game - and it would be interesting to have e.g. three civilizations for snow, desert, and normal terrain, each with their own advantages in their biome.
Some of your suggestions are already implemented in the (full) game, like teams/alliances and sacrificing units.
I'm not sure what you meant by "hard to select units" without having seen a video. I saw something similar in a gameplay video and already made some changes to better select units on tiles.
And if I understand you correctly, the third characteristic in the UI, besides health and damage, is the hotkey to quickly spawn the unit.
And yeah, terrain that influences the fight is something I am currently working on (mountains where only archers/cannons are useful).
I also like the idea that units that died inside the round will only reset the population counter after the round ends. Although I am pretty sure that some players might think that's a bug if not explained well.
Like I said, big thanks for your thoughts!
Aside from your suggestions, have you encountered any bugs or glitches or just things that don't make sense?