Installing Half-Life mods is usually a simple process, but some mods have different installation methods. Follow these steps:

First, you need to download the mod itself. Mods can usually be found on websites such as ModDB or other Half-Life communities.

Extract the mod files (usually stored in formats such as .zip, .7z, or .rar) into your Half-Life directory, the folder where hl.exe is located.

If the mod comes with an installer, check how it installs: does it install as a separate mod folder, or does it include a complete game installation with its own executable?

To check this, install the mod in a temporary folder (for example, a folder on your desktop) and look at the contents:

• If it contains a folder with the mod name, it is usually safe to move that folder into your Half-Life directory.
• If it contains its own .exe file, the mod may include a standalone installation. In that case, move only the mod folder to your Half-Life directory. Installing it incorrectly may overwrite files, corrupt your installation, or cause Half-Life to behave strangely.

To start the mod, open hl.exe and select it from the "Change Game" menu.

On some Half-Life No-Steam versions, this method can sometimes cause crashes. There are other ways to launch a mod:

• Create a shortcut for hl.exe (or use a .bat/.cmd file) and add the following launch parameter:
  
  -game mod_folder_name
  
  The name must be the same as the mod's folder name. Example:
  
  -game clanniversary
  
  You can also add -steam to make the game run as if launched through Steam.


• Launch it through Steam. After installing a mod, it may not appear immediately. Restart Steam or wait until Steam decides to notice it (which can take forever).


• Add the parameter -game mod_folder_name in Steam's launch options:
  
  Steam Library → Half-Life → Properties → Launch Options

The mod should now launch correctly. Enjoy playing!