Restrictor

"Perimeter... Restrictors... Disengaged..."

- Combine Dispatcher

Restrictors (also commonly referred to as Thumpers by Resistance members), are large, monolithic devices used to send pulsing thumps through the ground to keep Antlions at bay.

Technical information
The Restrictor is a very effective device for defending oneself from Antlions. Restrictors are deployed by the Combine but are used by both sides. A Restrictor must have an external power source such as a generator in order to operate. To turn a Restrictor on or off, look for a switch on its' power source or on device itself and press it.

Restrictors use three plates of a metal and controls them by use of magnetics. The sheets of metal are pulled up in a one-by-one fashion, and then are dropped together with excessive force, sending a powerful vibration through the ground which can easily overload the senses of Antlions.

Usage
The Combine use Restrictors extensively in the Antlion-infested regions, placing them in strategic areas to stop Antlions from accessing important structures or areas.

Nova Prospekt was surrounded by a network of Restrictors to keep the Antlion hordes at bay. When Gordon Freeman attacked Nova Prospekt with the Antlions at his control, he had to disable a number of the devices to allow his Antlions to assist. It is important to note the speed with which these Antlions take hold in the facility, breaking into the outer prison areas in overwhelming numbers in less than an hour after the defenses are deactivated.

Behind the scenes



 * In the early stages of the game's development, the Thumper was to be a small, usable item, in the form of a yellow fire hydrant (though this may have been just a temporary placeholder model), and nicknamed "rollerbuddy". The player was to carry only one at a time and could put it on the ground to achieve to same effects as the larger, stationary versions in the retail version.
 * In early Wasteland maps, early brush Thumpers can be found.

Trivia

 * In the original Half-Life, similar machines appear on Xen. While their structural appearance is different, both emit thumps through the ground. This is probably why no Antlions appear on Xen even though that is where they originate from.

List of appearances

 * Half-Life 2
 * Half-Life 2: Episode Two