This world might have been around for long now, but there is still plenty of space (maybe not that much in the US...), see for yourself in the maps below:North America
Omitted are Bogota and a few hubs with fewer than ten flights.
Big airports with no airlines based (or very few flights) are shown below. Red colour is for airports larger than 30 000 000 passengers and violet is for smaller than that.
London is Gatwick airport, Shanghai is both Pudong and Honqiao, Tokyo is Narita, New York is La Guardia and Moscow is all.
(EDIT on Jan 3rd: Shanghai Pudong and Bangkok are now taken)
In-game forum is here, it's lively and so is the aircraft market.http://www.airlinemogul.com/world_info.php?wid=3154