SMOD 40a Piped! Full

                    
SMOD is a single player mod of Valve’s first-person shooter Half-Life 2. The new content consists of many new NPCs and weapons, new gamemodes, comprehensive customization and tweaking options, new abilities for the player, and new features to the gameplay, such as level randomization and simple branching in the otherwise linear flow of the main episodes.
Requires you to have the Source SDK Base (2006) installed to play.