The map works best on Half-Life 2 and Half-Life 2: Episode One but can also be played in Half-Life 2: Episode Two.
This mappack tells a story of a man who finds himself in a dark drainage after escaping two combines. His journey takes him through a sewer system that is now ridden by headcrabs and zombies. Later he catches the attention of combine forces while driving through canals with a water boat. The action gets hectic when the combine try to stop this rebelling citizen.
Being one of the largest and best single-player campaigns for Half-Life 2, the map has got really good comments and is really worth playing.