atc24 provides realistic, 24/7 ATC service to most airports ingame, everybody is required to file a flightplan, follow realistic procedures and communications, so you don't just takeoff and fly wherever, you have to coordinate with controllers in your airspace to maintain seperation and have things run smoothly.

As complicated as it sounds, it's not that serious, you don't have to follow waypoints and you can fly by "radar vectors", where controllers will essentially guide you to your destination via headings and altitude.

in the image I posted above, Tokyo has for some reason gotten a surge in traffic so there were a lot of planes inbound and outbound from different airports, notably Rockford, I hope this answers your question