Authors of modification: Obsidian Conflict command
  The made changes: guns, locations, cooperative mode
  Version: 1.1
  It is necessary: game HalfLife 2 and Source SDK Base
  It is desirable to have: Counter-Strike Source, Half-Life Source, Half-Life 2: Episode One; Half-Life 2: Episode Two
  Size: 450 mb

Modification adds a large number of the modes of game: from the normal cooperative mode and to the fishing mode. Modification in places reminds a gameplay of Left 4 Dead. Shoot crowds of the zombie and you catch a small fish small more. Pleasant passing!

Installation instruction of modification:
  Download and unpack HL2_Obsidian_Conflict.rar archive. Launch the OC-Beta1.34_Full.exe file. After installation a mode, set a patch 1.34, having launched the OC-Beta1.34_Patch.exe file.