DOSBox
DOSBox is a free and open-source emulator which runs software for MS-DOS compatible disk operating systems—primarily video games. It was first released in 2002. Before Windows XP, consumer-oriented versions of Windows were based on MS-DOS. Windows 3.0 and its updates were operating environments that ran on top of MS-DOS, and the Windows 9x series consisted of operating systems that were still based on MS-DOS.