- The Emplacement Gun is used by the Overwatch forces to lay down suppressing fire on groups of rebellious Citizens in bunkers, on barricades, and other fortified positions suitable for placing a mounted machine gun. Rebels also use captured Emplacement Guns to protect Resistance bases such as Shorepoint Base or the Vortigaunt Camp from Antlions.
- It is held with two handles, one of them apparently housing the trigger. Using it to shoot rapid fire pulses directly into the enemy is a simple but effective method of destroying groups of enemies.
- Due to the apparent lack of trigger, the gun may utilize the butterfly trigger system, in which the weapon is fired by squeezing the handles towards each other.
- A usable Emplacement Gun normally hints at many enemies incoming.
- When activated, the three panels protecting the cannon expand, releasing it, and the whole device slightly rises above its mount.
- When used by a friendly NPC, the player can use it by pressing the "USE" key to gain control of the Emplacement Gun, such as when Alyx is operating it.
- The Emplacement Gun includes a built in flashlight, automatically switched on (during nighttime) when the post is manned.
- When idle, the NPC manning the weapon randomly positions itself in left, right, up and down positions.
- On the body can be seen the alphanumerics "V952", also featured on other Combine devices.
- It is the Source equivalent of the GoldSrc M2 Browning Machine Gun. Fittingly, it does very high damage, nearly twice as much as the Pulse Rifle. It is also a counterpart to the heavier M198 Howitzer and HECU Double Turret.
- The Emplacement Gun is very powerful because of high rate of fire and high damage; only a few shots are required to kill most enemies. However, the lack of rotation and peripheral vision exposes the user to attacks from the sides or behind, so one should always be ready to get off the gun when overwhelmed by enemy attacks or when being attacked from behind.
- The Emplacement Gun is supplied with unlimited ammo and has low recoil unlike the portable version, so the player can fire the gun in full auto without worries of running out of ammo or having to reload while fighting a group of enemies.
- Shooting the gunner directly with normal weapons is not advised because the barricade adds more protection for the gunner. Though this method can still be used, the player might lose a lot of their health if doing so. Other weapons like grenade can be used to force the enemy dismount it, making them an easy target. If the player waits too long, the target will eventually re-mount the gun again. The Grenade launcher from MP7 is also effective method to take the gunner out in one hit. Skilled players can use the Crossbow or the Colt Python to pluck the gunner with a headshot at long ranges, though this is not always recommended as when player gets hit, the player will flinch a little, and may miss the target. Another method is charging at the target when they are distracted by other enemies, such as Antlions or Rebels.
- When used by friendly NPCs, it is best to draw the enemies into the user's range. Especially the big threats like the Antlion Guard, Overwatch Elites and Shotgun Soldiers.
- Some players could resort to the tactic known as "Spraying and praying" or Blind fire if the player is overwhelmed by enemies.
The Emplacement Gun appears in the games in the following order:
- It is first seen at Station 12 in the Canals, mounted on a Combine Barricade. There a Metrocop uses it to kill Rebels. Gordon Freeman uses it afterward against Metrocops, and City Scanners. If the player does not proceed, an APC destroys one with their rockets.
- Another Emplacement Gun is used near the APC garage in the Canals, also by a Metrocop.
- When going back inside the APC garage before going back to the Airboat, a Metrocop uses a newly installed Emplacement Gun inside the building.
- At Shorepoint Base, Rebels use two Emplacement Guns to protect the pier from Antlions. Another is placed above the Vortigaunt Camp entrance, for the same purpose.
- Most bunkers on the beaches before Nova Prospekt are equipped with Emplacement Guns, manned by Overwatch Soldiers.
- In the courtyard inside Nova Prospekt, several Emplacement Guns mounted on watchtowers are manned by Nova Prospekt Prison Guards. Inside, one is found in cell block B4.
- Two Emplacement Guns are used by Metrocops during the City 17 Uprising, in the tunnel filled by Manhacks preceding the plaza where Alyx is kidnapped. Freeman is then allowed to use it against Manhacks and Overwatch Soldiers.
- In Episode One, the first Emplacement Gun is featured under an Overwatch Sniper nest.
- Right after, when Alyx takes on the Overwatch Sniper Rifle to provide cover for Gordon, an Overwatch Soldier is seen hidden behind metal plates firing at Antlions with another Emplacement Gun. Alyx quickly dispatches him after Gordon removes the metal plates with his Gravity Gun.
- A third Emplacement Gun is found on the large plaza where the Antlion Guard is fought. Alyx uses it to cover Gordon while he blocks the Antlion holes with cars.
- Another, unmanned Emplacement Gun is placed in the Technical Trainstation. It is mostly used by Alyx while Gordon escorts Rebels and Citizens to the platforms.
During their assault of White Forest, the Combine forces installed an Emplacement Gun in the secondary silo. Freeman quickly uses it to dispatch the remaining forces after closing the silo. This is its only appearance in Episode Two.
- Resistance members never mount the Emplacement Guns outside the Shorepoint Base and the Vortigaunt Camp. They instead prefer to use cover by crouching behind the barricade, which can be seen in the chapter Anticitizen One, in the tunnel when the player needs to wait for a Rebel to blow up a wall while a group of Manhacks and Overwatch Soldiers is coming. However, in Episode One and Episode Two, they will mount it when having visual contact with enemies while close to one.