Example:
Glass
Desert Sand
Jungle
Pine Forest
Moorland
Ice
Snow
And also extra level can be added so that more feature can be added.
For example
Level 0: Apron, road and remote gate departure and arrival
Level 1: Departure lounge
Level 2: Arrival corridor
Level 3: Departure corridor
Level 4: Shops and restaurant
Level 5: Business Class Lounges
Level 6: First Class Lounges
Level 7: 3 star hotel
Level 8: 5 star hotel
Level 9: Hotel facilities
Level 10: Observation Deck
main problem i can see with that is loading you are pretty much adding an entire map’s worth of object data per level this could have a large impact on game load times
While I do appreciate the ideas you are presenting, many who have built large airports with a lots of traffic per day already have problems running faster than the slowest level due to path resolutions for the currently supported 5 levels.
10 levels would really drag the Unity rendering to a crawl.
Personally, I already struggle with the existing complexity of the game and don’t need more levels to manage.
Just my thoughts.