We already have ground units so why not airplanes?
Make them unlocked after reaching a certain age and with a high level of technology, you can build them but they're very expensive and can break easily in battle, you need an Airport building to construct and store your planes, you can then select them and choose a province to either defend it (gives a defense bonus to your ground units) or attack it (gives an attack bonus to your ground units), they would mainly be used for support, and the more planes you have the higher the bonus is, but there's a limit of how many planes can be in a certain province, and if there are enemy planes in the province your planes are, then the bonuses will be lowered and the planes will engage in battle.
By Ciao Ciao
Welllll, these are some of my ideas to improve the game:
-better trade request: I was playing with Nazi Germany and I had all provinces of Greater German Reich exept for two siberian provinces owned by British Raj. I was the first in the leaderboard and Raj was 2th. I couldn't risk too much so I asked him to do a trade request: he gave me that 2 provinces and I would gave him 10.000.000 money. He refused.... I asked him another time with more of 10 million but he still refused. So I would like that trade request'll be better. For example with provinces trading. Also I've noticed that AI except for coalitions doesn't do trade request at all
-Add a brush tool in the game, so we can select multiple provinces and build buildings/raise happiness/stability ecc in one time
-Add a brush tool into scenario editor into relations so we can select a country and raise or decrease relations of multiple countries in one time
-better wars: damn... how can it be possible that Pakistan conquers all of China.... or that Poland and Belgium can destroy Nazi Germany
-select ideologies of our vassals when we create them
-improve the importance of ideologies because sometimes it happens that third reich is friend with UK and France but is enemy with Italy, or that USA and URSS are friends
-to add new editors like the goverment creator or to add suggested owners into a province instead to do it into AOC files because it's easier to make mistakes
-better alliances: I've noticed that AI never makes alliances with 3 or more members. Also In the game you can't edit the name of your alliance (I think)
-better colonies: as others have already said to give a name to your colonies like name of the nation + name of the region colonized like: Italian Guyana or Belgian South East Asia. Also to create a new tipe of vassal (the colony)
-and lastly to add revolutionary risk into the scenario editor instead to set to 0% the level of happiness
I hope you enjoyed at least one of these ideas and that at least one of these will be done.
Sorry for mistakes
An option that allows tribal civilizations to spawn randomly on the map, with a higher chance of appearing in high growth provinces.
Instead of building a army using money, scrap that and have it being that it require that province's population to build a army.
This will make so that your gold can not quickly build a army in one turn.
Example, you select provinces that will build a army for you based off of the population the province has.
Population of 25000, would be able to recruit a army of 1500 but it would take 3 turns.
Each turn makes 500 units
There needs to be a new building so that you can train a army. The higher the level the building is the faster and more units you can build.
The cost would increase the military upkeep.
This would allow a nation prepared for war, have a higher chance of winning.
Even if you are a small nation but have time to build up a army without costing gold would be ideal in terms for war.
A Big Nation will always out produce units because of gold but take that away then this allows a small nation to take down a big nation or at least get them to agree to a peace deal in the small nation favor.
Having these buildings in the game would allow strategic planning since now you know where you should plan your attack.
You would want to take out their building so they cant counter attack or build a army close enough.
With what we currently have a Nation with a high budget can build a army of 2500 in one turn, which is annoying because you probably was prepared for war but suddenly they out number you.