This is a pretty cool game (at least to me) which simulates being an ATC controller at one of a selection of airports around the world. There are only a small selection available 8 airports for free, which isn’t bad, unless you donate $20 (about £12), which seems a bit expensive, but you do get a choice of many more airports! It is pretty addicting if you know what the hell is going on, so it is recommended you read the tutorial. If you want to try it out, you can have a go here