Today's PCs and mobile devices are way too easy to use, because all you have to do is tap or click on icons. For my $2 bill, the command-prompt-centric MS-DOS will always be the operating system of choice. If you haven't had to type "dir/w" at a command prompt to find your files or swap through three floppy disks to play a game, you're not really computer literate.
The Google Play market has a number of DOS emulators you can run on any modern Android smartphone. DosBox Turbo is among the best of these, offering support for 3Dfx graphics instructions, MIDI sound and mouse / joystick emulation. You can find old DOS applications, including games, on several sites, though many of these are still copyrighted.