: You generally need Source SDK Base 2006 , Counter-Strike: Source , and Half-Life 2 installed for the classic version to function. Manual Install :
Download the "Garry's Mod 10 Classic" files from community archives like Steam Community groups or ModDB . Garrys Mod 10 Download PC Game
Garry's Mod 10 , released on November 29, 2006, was the first commercial version of the game published on Steam. While the current version of Garry's Mod on Steam is the most up-to-date version (often referred to as version 13), you can still download and play the specific "Garry's Mod 10" experience if you own the base game. Official Purchase and Installation : You generally need Source SDK Base 2006