Hexen II can be played:

  • Natively on OS's up to Windows 98
  • In DosBox for OS's Windows XP, 7 and 8

However best played on one of the source ports:

Hammer of Thyrion

UQE Hexen II There is a texture pack for this port but I haven't got it to work.

JSHexen II This is excellent and includes new terxtures, sounds, models etc. Its also easier to install as you just extract the Hexen2 directory and go.  No faffing about with the original game files.