Zombies instead of scientists are now found in the observation rooms. In Decay, the Hazard Course is visited when Gina Cross and Colette Green are required to cut through the destroyed remains of the Hazard Course to reach the surface with Rosenberg during the chapter Hazardous Course. Vortigaunts are swarming the area and attack the hologram, probably thinking it is a living being, but do not damage it. There the facility appears to have been damaged as well by the Resonance Cascade, and the Holographic Assistant is still working.

In the Opposing Force chapter We Are Not Alone, the standard Hazard Course can be accessed with the Displacer Cannon in the map the weapon is found in. The Hazard Courses appear as the optional training chapters of Half-Life and Blue Shift, the latter based on the same maps, although they are two different areas. The two known Hazard Courses are apparently built over old, disused industrial maintenance sectors of the facility, and are each divided into an obstacle course for physical training, and a target range for firearms training. Demonstrations are provided by trained instructors or prerecorded Holographic Assistants, whilst participants are constantly monitored by observing scientists. Encountered in all four of the original Half-Life games, Sector A's Training Facility contains the separate Hazard Courses used for training scientists (predominantly in the use of the HEV Suit in the standard 'Black Mesa Hazard Course') and security guards (in the 'Black Mesa Hazard Course for Security Guard Training').

Half life hazard course