Fairly simple. A person posts a photo of an airport and a hint of where it is (i.e. region, state, country, stuff nearby, etc.), then people have to guess where it is. Intelligent answers only, please . Photos can be of real-life airports or flight sim airports given that it has a reasonable resemblance to the real life airport. Finally, the airport must be a passenger airport with at least ~5 million passengers a year.
I'll start:
A busy airport in Canada.