Flightgear is a free, open-source flight simulator available for various platforms, GNU/Linux among them. It has more than twenty thousand airports, more than twenty airplanes, fully equipped runways, and other characteristics similar to those offered by other simulators like Microsoft Flight Simulator.
Flightgear is not really a game, but a simulator, so you'll need to learn how to fly before taking control of an airplane. In fact, the intention of Flightgear's creators is to create a professional and extensible (thanks to its open-source status) flight simulator that can be used for research and didactic purposes.
It includes many variables that can influence the simulation, and you can simulate a flight in a multitude of situations that you generate yourself, which considerably elevates the options available with this program.