For 64-bit Windows it's easiest to just use a DOS emulator like DOSBox http://www.dosbox.com/

Install DOSBox then extract dungeon.zip to C:\DOSGAMES\DUNGEON (Note: You'll need to create the DOSGAMES and DUNGEON directories in your C drive)

Launch DOSBox and type: (Note: Hit Enter after each line)
mount C C:\DOSGAMES
C:
cd \DUNGEON
DUNGEON.EXE

When your'e done playing type:
Quit
Y
Exit