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The Sentry, as it appears in Black Mesa. From left to right: idle, active and off.

Overview

The HECU Ground Turret, or Sentry, is an automated gun deployed by the military during the invasion of the Black Mesa Research Facility for unmanned defense against unwanted force or entry.

The Sentry is greenish in appearance, has 3 red dots on the top, is mounted on a tripod (which is very stable, despite its appearance), and has a small automatic 360° rotating gun [1]. Usually, there is a tripwire that is wired to the turret, but it can be activated in other ways.

Behaviour

When being triggered, the turret will emit a high-pitched whine and deploy its automatic gun, then proceed to shoot the trespassing organism regardless of whether it is human (unless it is an HECU Marine) or alien until it is dead, or the turret is knocked down. If the assailant goes out of the turret's view or dies, then it will proceed to shut off, until any other organism comes into its view.

Tactics

Except for its 360° rotating gun, the sentry doesn't move, so looking for a way around to avoid crossing its line of sight is a good move. Also, it is possible to damage the sentry with conventional weapons or even knocking it over with another physics object [2].

Media

Trivia

• The Sentry is a physics prop that can be pushed over, but cannot be picked up. [3]

Redesign History