Running Hexen 2 in the Hammer of Thyrion Source Port: 
  1) Go to the 
Hammer of Thyrion site and click on 
Downloads on the left hand side of the page.  
 2) On the 
Downloads page, click on either 
Windows version (32 bit) or 
Windows 64 bit version, then download either 
hexen2-1.5.9-win32.zip or 
hexen2-1.5.9-win64.zip. Of course, if you are using Linux or another operating system, choose the relevant link for your system from the choices listed on the 
Downloads page.  
 3) Extract to your folder of choice the contents of 
hexen2-1.5.9-win32.zip, 
hexen2-1.5.9-win64.zip, or its equivalent for your operating system.  
 4) Copy the Hexen II game files 
pak0.pak and 
pak1.pak into Hammer of Thyrion's 
data1 folder.  
 * 
pak0.pak and 
pak1.pak can be found in the 
data1 folder of your existing Hexen II GOG installation if you already installed Hexen II via the GOG offline backup game installer.  
 OR  
 * Alternatively, 
pak0.pak and 
pak1.pak can also be found and then extracted from the 
data1 folder of the Hexen II GOG offline backup game installer 
without installing the entire game. You can extract these two files from the Hexen II GOG offline backup game installer by using the Windows and Linux commandline tool 
Inno Extract with the following syntax, pressing 
enter after each command:  
 inno-extract -I data1\pak0.pak \path\to\gog-hexen-ii-offline-installer 
 inno-extract -I data1\pak1.pak \path\to\gog-hexen-ii-offline-installer  
 (If you are running Linux, use forward slashes, instead of backslashes).  
 * Please note the above commandline parameter's letter is the upper-case letter 
I, which stands for the word 
Include. For further information, read the 
Inno-Extract Man Page.  
 5) In the Hammer of Thyrion source port folder, update the game files to version 1.11 if necessary by running 
h2patch.exe.  
 6) Start the game by running 
glh2.exe.  
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 Running Portal of Praevus in the Hammer of Thyrion Source Port:   
Note: GOG does not currently sell Portal of Praevus due to legal issues that may or may not be eventually resolved between the two companies Microsoft (which owns Bethesda / ID / Zenimax) and Activision, so the only legal way to get this game's physical CD release is through Amazon, Ebay, etc.   1) Copy the 
pak3.pak file from the CD:\Install\Data\portals\ folder of the original installation CD, into the 
portals folder located in your Hammer of Thyrion source port folder. If the 
portals folder does not already exist there, create it now.  
 2) Create a shortcut to the 
glh2.exe file, add the 
-portals command line argument to the shortcut, then start the game.  
 * 
How to Create a Shortcut to a File or Folder   * 
How to Create Shortcuts with Parameters in Windows 10   3) 
To play Portal of Praevus, choose New Game.  
 4) To play the original Hexen II game, choose Old Game.  
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 To configure Hexen 2's and Portal of Praevus' music in Hammer of Thyrion, please also read:   
How to Set Up Hexen 2's and Portal of Praevus' Music in the Hammer of Thyrion Source Port