Made in USA by Microsoft in 1981
Supports only 4:3 displays (many of the used pixel resolutions wildly differ from this), so any screenshot produced for it should be adjusted to that for display purposes.
DOSBox or similar DOS emulator is needed to run DOS games and applications on modern systems (there are no DOS drivers for modern hardware devices).

Virtualization also provides alternative route to this. For that, the comparison of virtual machines at Wikipedia may prove helpful.

FreeDOS is a DOS-compatible operating system that replaces MS-DOS functionality but also expands the capabilities of what is usually expected for a DOS-compatible OS. Symbolic links, full 32-bit environment, 64-bit as well, multitasking, extended file names and attributes, hard drive sizes exceeding 16GB, USB drivers, Ethernet and internet, and drivers for some modern hardware. FreeDOS has even comes bundled with computers from companies like Dell and HP. FreeDOS can be installed on a computer but can also be used with the other two options (DOSBox and Virtualization)

Since all versions of pure DOS (not including the DOS versions bundled with Windows operating systems) are fully(?) backwards compatible (except MS 4.0), there's no reason to identify the versions any more specifically than blindly assume all games run on DOS 5.0 - the last real DOS (6.x added disk compression and after that the features were being stripped).

MS-DOS 4.0 was not the next step after MS-DOS 3.3. 4.0 was instead an update to MS-DOS 2.0 that added multitasking. It widely broke compatibility and caused regular freeze ups. Microsoft quickly replaced it with 4.01 that helped but did not eliminate the issues. IBM wisely chose not to base its PC-DOS 4 on MS-DOS 4.0 and instead updated 3.3 to create PC-DOS 4.00. When MS-DOS 4.0 became infamous, IBM made a very minor update to their PC-DOS 4.00 and released PC-DOS 4.01. PC-DOS 4.00 and 4.01 are indeed different from MS-DOS bearing the same version numbers. MS-DOS 4.0 was so infamous that makers of DOS clones did not use "4.0" as their version number. Digital Research skipped to "DR-DOS 5.0" (later causing their MS-DOS 5.0 clone to be labeled "6.0"). Novell DOS also skipped "4.0" and followed the same pattern as Digital Research. Since many customers chose to downgrade to MS-DOS 3.3, Digital Research also improved their DR-DOS 3.3 clone and labeled it DR-DOS 3.41. Even Microsoft president Jon Shirley later said, "maybe we shouldn't have called it DOS 4.0".

So, if a game lists "MS-DOS 4.0" in its system requirements, that it is certainly significant.

IBM PC-DOS 2000 (Not by Microsoft) was the last official DOS. It included the features of all previous version plus a few more and Y2K compliance. It did not include any of the problematic features (or lack thereof) of MS-DOS 7.x or 8.0. No games are known to have been written specifically for 2000.

tech info

resolution: 640 x 480 x 256 colors, 24 bit palette
memory: 8M
CPU: 486
sound: Soundblaster 16

Related systems

Windows 3.11992
Windows CE1996
Xbox 3602005
Windows Phone2010
Xbox One2013
Xbox Two2020