In Quake 2, the Black Hole Generator is a device situated in the Strogg capital city's main hangar complex, which is used by the Strogg to travel to other planets. It generates large black holes for ships to fly through, so that they can quickly arrive at their target. Based on the mission briefing in the manual ("It may be a long sleep back."), the Human forces used captured Strogg black hole technologies to launch their counter-invasion of the Strogg homeworld, possibly co-opting the Black Hole Generator itself in the process. Its destruction is the main objective to be found at Launch Command if the Hangar hub and will leave the Human forces stranded on this side of the galaxy with no quick way home.
The Generator is powered by a large CPU manned by a small crew of personnel. The CPU can be shut off by cutting off the coolant pipes in the facility controlling the Generator. Once the CPU is down, the computers and personnel operating the Generator must be destroyed for the Generator to be disabled permanently. This is easier said than done, because of its significance to the Strogg and their need to capture and assimilate alien races. The whole facility is heavily defended by Gunners, Gladiators, Iron Maidens and Tanks. Technicians, also able to help defend the facility from attack, are permanently stationed therein to perform essential maintenance, and Guards stationed in and about the complex perform all of the more menial tasks, including operating the Black Hole Generator and guarding its core computers.
The technology in the Dark Matter Gun might be based off the Black Hole Generator. Besides the appearance of a gyroscope-like assembly, it can create and fire miniaturized black holes at targets. It is another example of the frighteningly swift technological advances the Strogg continue to make, even while Mankind's invasion forces are in its midst.
The Black Hole Generator is credited in Quake 2 with allowing the Strogg to launch lightning fast invasions of alien worlds, however in the opening video sequence of Enemy Territory: Quake Wars, a gigantic Slipgate is seen being used by the Strogg to invade Earth, and not a big black hole, suggesting that the Black Hole Generator may simply be the creator of the portals contained within the framework of the Slipgate itself, possibly due to a stabilizing influence it may have on the portal.