For questions related to games running on MS-DOS, a family of text-based operating systems for IBM PCs and compatibles of the 1980s and 1990s
DOS (Disk Operating System) is a generic name for the simplest possible operating system that can handle a disk. Examples abound from the 1950s onwards, from all major manufacturers. IBM and Digital Equipment Corporation (among others) supplied a DOS as a bootstrap operating system used to generate larger ones.
The best known and most commonly used examples of DOS are for the IBM PCs and compatibles of the 1980s and 1990s. Members of this family include Microsoft's MS-DOS, IBM's PC-DOS, Digital Research's DR-DOS, Novell DOS, FreeDOS, and others.
Between enthusiasts and legacy environments, there remains a high level of interest in MS-DOS systems and applications, whether running on real vintage hardware or under a virtual machine such as DOSBox.
Early consumer versions of Windows (the 9x series, up to Windows Millennium) were built atop of or partially based upon MS-DOS. Windows NT, Windows XP, and later do not use MS-DOS.