The game is not “abandoned” but it is released and finished for it’s full 1.0 state. Just head over to Airport CEO 1.0-0 released and you’ll see that the game is receiving occasional quality of life updates.
Airport CEO is unfortunately not a live service game with a subscription payment model result an endless flow of new features. Hopefully there will in the near future come along a more complete airport tycoon style game that ticks all the bullets in your list, although I do believe that ACEO at least does have both baggage and economy and business class passengers! I myself will be waiting for that game at least, playing your own game doesn’t really scratch “that itch”.
That is very unfortunate, as the game is great and I feel like the frame work is later to make it better.
I know I would and I’m sure a lot of other players would pay to download expansion packs with new features. That can be added to the game.
I would also love a full style 3D tycoon game that would be amazing but I think you guys have done a very good job just some small improvements would make it better.
There would be for sure people paying for DLCs. And there are endless of ideas which would the game make very nice.
But from an economical point, Apog Labs with 3-4 devs cannot survive spending months of development for DLCs which usually are cheaper and bought by less people than the main game.
If they do that, at some point, they would be trapped in the current game and won’t have budget for a complete new and better game.
It’s not like Colossal Order with a big investor in the background, allowing an entire department continuing working on DLCs for the previous game, while others work on a new game.
The only hope I have is, that there will be a new game coming of this genre, catching up the best features of ACEO and other games of this type and add even more cool stuff.