1.Download latest GZdoom from my github repo or from https://zdoom.org/downloads
2.Extract and copy/paste into your game installation directory: C:\Program Files (x86)\Steam\steamapps\common\Hexen\base
3.Rename the dosbox in your directory to dosboxold
4.Rename gzdoom to dosbox
5.Run the game from the desktop shortcut
6.In the GZDoom Welcome menu select Hexen:Beyond Heretic
7.For Video Settings Select OpenGL
8.Select Don't Ask Me Again checkbox in order for the menu not to show up every time you launch the game
9.To add more authenticity if sprited monsters feel too smooth change setting in the Options>Texture Filter mode to None(trillinear)