I've been a fan of ATC Simulator for years now (Versions 1 and 2), ever since it was first released. (I loved Kennedy Approach at the time too and even started on these types of air control simluation with some basic C64 game in the early 80s). Anyone remember Tracon, by the way?
Probably boring to most, but nail-bitingly intense for me, and ATC Sim 2 has been on my hard drive for years, which is something I can't say for most other games.
It's a bitch to get the voice recogntion to run, but once that's done there's endless amounts of suspense here. An unbelievable amount of geographical areas, scenarios (one for each hour of the day for each area), and a randomizer to boot.
Szenarios ranging from snoozefest (Buttfreck, Missouri at 6 a.m.) to superhuman (prime time LA) and everything in between.
ATC Simulator was programmed by only one guy who really knew what he was doing.