Restrictor

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

- Overwatch Voice

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

Overview
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, the player must 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.

There are two types of Restrictors. The most common type, found throughout the Coast and within and nearby the Victory Mine, is relatively small, while the ones around Nova Prospekt are larger and presumably more powerful, with their activation switches located at the top of a ladder.

Use
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 also to have a portable version. It can be found and used in the playable Half-Life 2 Beta, where a yellow fire hydrant is used as a placeholder model. It was simply named "Portable Thumper". The player was to carry only one at a time and put it on the ground to achieve to same effects as the larger, stationary version. A second model, not appearing in-game and named "heavy", was probably a more powerful version.


 * In early Wasteland maps, early brush Thumpers can be found. They also appear as models in the playable Half-Life 2 Beta files, the hammer being a separate model.

Trivia

 * In the original Half-Life, similar machines appear on Xen. While their structural appearance is different, both emit thumps through the ground.


 * A Restrictor can be spawned into the game by " " but it spawns on top of the player. Noclipping is then required.

List of appearances

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