Answer: Flight Simulator

Upon first consideration it would be easy to assume that MS-DOS (or Microsoft Disk Operating System) was the longest running software line produced by Microsoft. After all it was their first major product before Windows. While it’s an early example of a popular and important Microsoft product, it’s actually not their longest running product line as its final release was back in September of 2000.

What about Windows? It was first released to the market in November of 1985 and surely that must count as Windows is still going strong. Windows is outpaced (by a margin of three whole years no less), however, by Microsoft Flight Simulator.

That’s right, the flight simulation game that has allowed multiple generations of children and countless frustrated adults to fly among the birds and then smash their plane to bits thanks to the trickiness of sticking a good runway landing has been around for four decades and is still going strong.