Gut Reaction

Gut Reaction is a Single-Player Mod for Half Life. It was Developed by Theunbeholden and Released on November 15th 1999.

Overview
Gordon Freeman has Once Again being recruited by the Mysterious G-man to handle a "Situation that could prove Castastrophic if not Handled immediately. It seems that a Rift in the Space-time Continum has allowed the Aliens of Xen to establish a stronghold inside one of the main reactor cores in the Lamda Complex. Somehow they have figured out a way to tap directly into the complex's Nuclear Power Grid. They are Using this Energy to Continually widen the Rift to Allow Numerous Xen Creatures into Earth.

Links

 * Gut Reaction
 * http://www.moddb.com/mods/gut-reaction/downloads/gut-reaction