This mod (mappack) is made in the form of old school shooters and shoot. You have to go through a path of 5 levels killing all who will fall into your eyes. For the game you need HL2 EP2. Unpack the archive in the folder "Map", in the game open the console and enter "Operation_X_01"
Old skool this definitely is - and I loved it. Sure, it's hardly HL2 but more like something from the 90s, which is just ace. I really enjoyed this map pack!! :-)
Great gameplay, but could have better map detail. Also, if I were to leave, and then re-enter a map, it would make all of the physics objects appear in different locations. Other than that, great map!