Installation Instructions mod Decay: Singularity
Extract the decay_single folder and place it into the root directory of the game.
Launch the game, go to the Change game menu, and select the mod.
Play!
To avoid entering the "Change game" menu every time you start the mod, you can:
Option 1: Launch via shortcut
Go to the properties of hl.exe and in the Target field (for example: "D:\Games\Half-Life\hl.exe") add a space and then write -game followed by the name of the mod folder in the game root directory. It should look like this: "D:\Games\Half-Life\hl.exe" -game mod_folder_name
Apply the changes.
Launch the mod using this shortcut.
Option 2: Launch via Steam
Open Steam, click on the "Games" menu > "Add a Non-Steam Game".
Browse to the game folder and select hl.exe.
A shortcut will appear in your library.
Right-click on it, select Properties, and in the "Launch Options" field write the full path to hl.exe (for example: "D:\Steam\steamapps\common\Half-Life\hl.exe") and add -game plus the mod folder name after a space. It should look like this: "D:\Games\Half-Life\hl.exe" -game mod_folder
