Mark IV Thermonuclear Device
|Mark IV Thermonuclear Device|
The bomb is first mentioned by two Black Ops assassins in a storage area. Later in the game, in the thirteenth chapter, "The Package", Shephard discovers two other Black Ops assassins setting up the bomb in an underground parking lot under the large Ordinance Storage Facility and connected to Sector E Materials Transport. After killing the assassins, he deactivates it. Afterwards, he proceeds to a nearby room with a view on the truck, and witnesses the G-Man reactivating it. He cannot return to the truck, making the destruction of Black Mesa inevitable.
The bomb detonates when Shephard is detained by the G-Man aboard an Osprey at the end of the game. He witnesses a white flash from the horizon that blinds him while the G-Man makes a slight pause in his monologue, marking the destruction of the Black Mesa Research Facility.
The following instructions are written inside the bomb's cap:
- MANUAL INSTRUCTIONS FOR A:
- MARK IV THERMONUCLEAR DEVICE
- This device carries a GRADE C plutonium control detonator.
- With this device an approximate safe distance of
- 55 kilometers is recommended.
- Indispose the gravatronic rev limiter to 11.
- Rotate red knob to the on position.
- Press button labeled B.
 List of appearances
- Half-Life: Opposing Force (First appearance)