So I've found this interesting game,
Airline Empires. Basically, you run an airline in a competitive world, and try to succeed. It's pretty cool, but borderline geeky. Unlike most games, this is not about flashy graphics and exhilarating gameplay. This is a straightforward but deep airline management simulation, and the entire interface is effectively a website; a plane is nothing more than some unique parameters and a pretty photo.
It's completely free and remarkably challenging, so I strongly recommend giving it a shot. The game progresses in real time, at a rate of 2-4 days an hour. Unlike many similar games, such as Airline Manager on Facebook, you do not need to manually activate anything to keep it going; you can make changes, but the airline can and will run on autopilot
(pun intended). Of course, it's ideal to be making a killing, then sit on the positive gradient.
It's fairly realistic, more so than some others, but it's a very serious type of game; there are ex-wargamers who get into Airline Empires and build strong airlines and strong alliances to crush any and all opposition. Which is hilarious, but also simulates the real world of airlines - it's cutthroat as hell, and even the best airlines cannot sit around.
So far, I've got one MD-83 shuttling between KUL and SIN, 42 times weekly. I'm not quite profitable, but we shall see. Unsurprisingly, I've called this airline WatsonAir.
I also think this is a very good base for a macro railway armchair simulation; this is the sort of game I've been looking for, with a focus on hard numbers and hard realities.