DOSBox
DOSBox is an emulator that emulates an IBM PC compatible computer running MS-DOS. It can run many MS-DOS games. You can find a list of compatible games here.
DOSBox works wit a command line, but there are some graphical frontends:
AmpShell
DBGL
D-BOX
DOSBoxGui
GR-lida
GOG.com is company that sells many great old DOS games for $5.99 or $9.99.