X-Plane! http://www.x-plane.com/ http://www.x-plane.com/ In active development, unmatched flight model accuracy, huge community of aircraft, scenery, and plug

X-Plane! http://www.x-plane.com/ http://www.x-plane.com/ In active development, unmatched flight model accuracy, huge community of aircraft, scenery, and plugin developers, fly online in VATSIM and IVAO, excellent systems and failure modeling... You can even buy a USB-Key that makes it FAA-certified!