This is a Half-Life 2 single-player mappack of 4 maps.

This is a story of a citizen who escapes a few cops. He runs to an alley and finds a hole in the ground that leads to the drainage. The cops doesn't follow him but now he's trapped in the drainage and have to find a way out.

To play extract everything into your hl2 directory and type "map drainage1" into console in game.