YS Flight Simulator is a free but fully featured flight simulator. You can use YS Flight Simulator to fly more than 40 types of airplanes.
Features: dogfight, ground attack, formation leader, take off & land the aircraft carrier, try cross wind landing, network play vs your friends, and more.
The program will also let you specify command mode parameters to immediately start the server mode or the client mode — e.g. fsmain.exe -server Yourname, fsmain.exe -client Yourname ServerAddress
YS Flight Simulator does not feature ‘state of the art’ graphics, but it will do the simulation job.