Zero Point Energy Field Manipulator
For other uses, see Gravity Gun (disambiguation).
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The Zero Point Energy Field Manipulator, more commonly known as the Gravity Gun, is a gravity-based device, originally designed for handling hazardous materials, but, as Alyx Vance stated, is now primarily used for heavy lifting. At its core is some sort of gold-colored substance. Introduced to Gordon Freeman by Alyx shortly after his arrival at Black Mesa East during Half-Life 2’s fifth chapter Black Mesa East, the Gravity Gun soon becomes an invaluable tool in Gordon's arsenal, and is now considered one of his signature weapons.
- The Gravity Gun has two basic modes. The primary fire releases an energy blast, which pushes the targeted object with a tremendous force. This is useful for clearing out barriers, or moving objects that cannot be picked up, such as disabled cars. The secondary fire picks objects up, and holds them just ahead of the device. These objects can then either be dropped by pressing the secondary fire button a second time, or they can be pushed with the primary fire. The secondary fire can only pick up lighter objects, mainly those which Gordon himself can carry, but the primary fire is capable of pushing much larger objects even if the secondary fire cannot affect them. The gun cannot affect most organic material, though there are a few exceptions.
- Using the Gravity Gun's secondary and primary fire modes in conjunction allow it to be used as a powerful weapon. Since it uses physics objects rather than conventional ammunition, there is virtually no limit to how many times it can be fired. However, this advantage is balanced by the need to "reload" after every shot, by grabbing a new object. Depending on the object fired, the Gravity Gun can be one of the most damaging weapons in the game. Heavier objects like metal barrels and propane tanks can even kill an Overwatch soldier with a single blast, but conversely, objects such as plastic crates, plastic bottles or wooden pallets will do very little to no damage due to their weaker materials. Explosive barrels, in particular, are highly devastating when used with the Gravity Gun, but this can backfire if the barrel is shot by an enemy while being held by the gun. The Gravity Gun is most effectively used as a short to mid-range weapon, since the physics objects it uses for ammunition are affected by gravity once they leave the device's hold.
- Ravenholm was built around the use of the Gravity Gun, as it contains most physics elements seen during the series. Indeed, one of its early names is "Phystown".
- The Gravity Gun is also handy for moving trapped vehicles, such as the Scout Car, as well as the Muscle Car. This is particularly efficient for flipping the Scout Car, if it flips over onto its roof.
- In addition to its use as a weapon, the secondary fire of the gun can be used to pull objects over from a distance, allowing Gordon to access supplies or other objects, that are out of reach or behind a Force Field.
- It can also be used as an alternative to the crowbar, in order to smash supply crates open (by picking them up and pushing them into the floor), which is faster than using the crowbar, and becomes mandatory during the first half of Episode One, during which Gordon is without his crowbar, until Barney Calhoun gives him a new one in the game's fourth chapter, Urban Flight.
- Another useful strategy is throwing back a Fragmentation Grenade to its sender. This can be dangerous, however, as the grenade can detonate while the player is holding it.
- The Gravity Gun can also be used to grab larger objects, such as metallic plates or radiators, and holding them up as makeshift shields. This was demonstrated by Valve in the E3 2003 demonstration Traptown.
- Larger objects, such as disabled cars, or even some pieces of furniture can only be pushed using the primary fire. Cars can kill several enemies at once and are also useful in Episode One, when Freeman must block several Antlion holes with them.
- It should be noted that the secondary fire of the Gravity Gun does not automatically tractor in targeted objects. The object must be brought within a certain distance for the field to directly capture it, during which time it is still subject to gravity. The gun must also be constantly trained on the object to maintain the effect, until it has been captured.
- In addition to its primary uses, the Gravity Gun can be used in more esoteric ways. Manhacks, City Scanners and Shield Scanners can all be held and punted by the gun; the first, in particular, can be held by the gun for use as a makeshift chainsaw. All three are heavy enough to deal significant damage if pushed, and will be destroyed if pushed into a nearby wall. However, if pushed over greater distances, they will stabilize their flight. It can also be used to grab and recalibrate Hopper Mines, or removing Rollermines from vehicles. A Rollermine grabbed in such a manner can be reprogrammed by Alyx to attack hostile targets instead of friendlies, and can also be pushed into enemies directly. Combine Sentry Guns can also be manipulated by the gun (disabled by being thrown when being enemies, replaced after being knocked down when being friendly).
- Though the gun cannot affect most organic matter, Headcrabs and Antlions are vulnerable to the primary fire. Three blasts from the primary fire will kill any Headcrab. Antlions are harder to kill in this manner, but being hit by the gun causes them to flip over, exposing their weaker undersides.
- The Gravity Gun appears to be quite heavy, as Alyx Vance and other characters that attempt to use the gun have some trouble lifting it. It also has significant recoil, as demonstrated when Alyx uses it to push a train door away. However, Gordon Freeman's HEV Suit presumably allows him to use the device with ease.
- Judith Mossman takes the Gravity Gun very seriously, and advises Alyx to do the same in her infamous sentence "The Zero Point Energy Field Manipulator is not a toy, Alyx!".
- The tutorial for using the Gravity Gun takes place in Black Mesa East's outdoor scrapyard, in which Alyx teaches Gordon the basic actions and uses of the device, notably by playing fetch with Dog and his own reprogrammed Rollermine, until they are interrupted by a Combine attack, forcing Gordon and Alyx to separate.
 Common objects
Most common objects found in the environment that can be picked up by the Gravity Gun and thrown at enemies, among others. Non-exhaustive list.
Includes "random" items found in the environment. Some items are very light and thus useless for gameplay. Some are heavier and can be used against opponents.
Watermelon. Has no actual purpose.
Environmental explosives that can also be detonated with bullets, and may backfire when shot at by enemies.
 Useful items
Also includes every single weapon and ammunition. All health/armor pickups are based on the 100 point limit.
Supply crate. Can be destroyed faster than with the crowbar.
Medkit. Instantly heals upon player contact.
HEV Suit battery. Instantly grants armor upon player contact.
Emergency flare, introduced in Episode One. Lights up when picked up. Can be thrown and picked up again until it consumes itself.
Car battery, used in a puzzle along the Coast.
 Dark Energy-powered Gravity Gun
- When exposed to the Confiscation Field in the Citadel, the Gravity Gun is "supercharged", rather than being vaporized as Gordon's other weapons are. It also cripples the field itself in the process. Once supercharged, the Gravity Gun emits blue light rather than orange, quakes in Gordon's hands, and creates small bolts of energy across its muzzle. Its powers are vastly enhanced, enabling it to manipulate objects of far greater mass than it could normally (such as Combine interfaces), as well as pull and repel them with greater force.
- Its most significant enhancement, however, is its ability to manipulate living, organic matter. Any Overwatch unit pushed by its primary fire is instantly killed, and their body retains an energetic charge, that will kill others if it strikes them. If grabbed by the gun's secondary fire, they are likewise killed instantly.
- It also has the side effect of vaporizing any weapon the soldiers are carrying. Interestingly, this also occurs when Alyx kills an enemy herself, using her handgun.
- Energy Balls can also be picked up and sent flying towards enemies, similar to the OSIPR's secondary firing mode.
- The first time the Gravity Gun is supercharged is in Half-Life 2’s thirteenth chapter, Our Benefactors, when Gordon's Prisoner Pod deposits him into a Confiscation Field; it remains supercharged until the end of the game. During this time, Gordon's HEV Suit also becomes 'supercharged' to the point of harboring 200% energy, and Combine energy chargers can even restore Gordon's health as well.
- At the start of Episode One, it is no longer supercharged, but becomes supercharged again after Gordon and Alyx re-enter the Citadel to stabilize the core, when Gordon accidentally enters another Confiscation Field. It remains supercharged until Gordon reactivates the core's containment field, at which point the Gravity Gun reverts to its normal state, presumably due to a significant dark energy drain effect.
 Related Achievements
|Any Half-Life 2 game|
|Bone Breaker (5G)|
|Kill 30 enemies with thrown physics objects.|
|Deadly Harvest (5G)|
|Kill an enemy by planting a Hopper Mine.|
|Hack Attack! (5G)|
|Kill five enemies with a Manhack.|
|Hot Potat0wned (10G)|
|Kill a Combine soldier with his own grenade.|
|Kill five enemies with the same Energy Ball.|
|Think Fast! (10G)|
|Kill an Elite Soldier with his own Energy Ball.|
|Zero-Point Energy (5G)|
|Get the Gravity Gun in Black Mesa East.|
|Two Points (2G)|
|Use Dog's ball to make a basket in the scrapyard.|
|Zombie Chopper (25G)|
|Play through Ravenholm using only the Gravity Gun.|
|Kill an enemy with a toilet.|
|Disintegrate 15 soldiers by throwing them into a Combine ball field.|
|Half-Life 2: Episode One|
|Grave Robber (5G)|
|Steal a Zombine's grenade.|
|Use flares to light 15 Zombies on fire.|
|Car Crusher (5G)|
|Use the cars to squash 15 Antlions in Episode One.|
|The One Free Bullet (40G)|
|Finish the game firing exactly one bullet. Grenade, crowbar, rocket, and Gravity Gun kills are okay!|
|Half-Life 2: Episode Two|
|Grave Robber (5G)|
|Steal a Zombine's grenade.|
|Puttin' On a Clinic (15G)|
|Defeat the chopper in Episode Two without any misses.|
|Kill a Hunter with its own flechettes.|
 Behind the scenes
- During Half-Life 2’s development, the Gravity Gun had several names, including: "Zero-Point Gun" or "prototype physics manipulator". Another weapon, the Physgun, whose model resembles the final Gravity Gun model, is present in the Half-Life 2 leak and was used as a gameplay prototype for physics manipulation and to demonstrate the physics simulation capabilities of Source at E3 2003.
- As heard in sound files featured in the Half-Life 2 leak files, Eli was to explain to Gordon at Black Mesa East, that while Black Mesa was a "decade away from harnessing the zero-point energy field", it turned out that the Combine had already pioneered this technology. He then explains that the Gravity Gun is based off "a little piece of tech Alyx liberated on one of her expeditions". He also calls the Gravity Gun's secondary fire mode "asymmetric". The Gravity Gun's "grand daddy" was used to manipulate hazardous materials in the Combine's portal reactors, suggesting the Gravity Gun uses Combine technology.
- At some point during Half-Life 2’s development, Ravenholm was set at the end of the Canals, and preceded Black Mesa East. Consequently, it didn't include the Gravity Gun, and as such, its gameplay only focused on Father Grigori's intricate traps (hence the name being used at that time, "Traptown").
- The Gravity Gun bears a vague resemblance to the Anti-Mass Spectrometer from Half-Life, notably the prongs. The Aperture Science Handheld Portal Device from the Portal series has some similarities as well; it was actually originally based on the design of the Gravity Gun, as seen in early Portal screenshots. It retained the prongs in the final design, as well as an zero-point energy field manipulator, allowing it to pick up small objects, but not throw them. The Gravity Gun can also be seen in the Enrichment Center lab where Doug Rattmann and Henry are working prior to GLaDOS killing its inhabitants, in the comic Portal 2: Lab Rat. Interestingly, in that same comic panel, we can also see two Black Mesa health and energy chargers, as well as what seems to be a Combine health charger. Whether these appearances were meant to be mere easter eggs, or perhaps have some meaningful relevance to the series' narrative remains to be seen.
- Exactly how the Gravity Gun works is unknown, but some conclusions can be made. It is possible it uses a Xen crystal, as the material inside the emitter is almost identical to a sample being studied in Eli's lab in Black Mesa East. When the gun is supercharged by a Confiscation Field, Overwatch describes it as a "counter-resonant singularity device". Because of this, it probably contains negative mass, or exotic mass. Negative mass is believed by scientists to have inverted gravity and repel normal mass instead of attracting it. The Gravity Gun may possibly control the gravity attribute of the crystal, making it able of both attracting and repelling objects. How the weapon should be able to concentrate the gravitational force at a single object is, however, not explained.
- When the player dies using the supercharged Gravity Gun, it disintegrates.
- In Episode One, during the sequence where the supercharged Gravity Gun is used, enemies killed by Alyx will still lose their weapons as if hit by the Gravity Gun. This is likely a small oversight, as the purpose of the Gravity Gun destroying enemy weapons is also to prevent the player from taking them during the sequence.
- The film District 9 features an alien weapon influenced by the Gravity Gun, built into a powered armor suit. It is able to pick up almost anything, including a pig, and hurl it with incredible force. It appears to have a much stronger field since it is also able to halt bullets and in fact keep them in an area just ahead of the muzzle, somewhat similar to a zero point energy field.
 HUD icons
 List of appearances
- Half-Life 2 at E3 2003: Traptown (First appearance) (Non-canonical appearance)
- Half-Life 2
- Half-Life 2: Deathmatch (Non-canonical appearance)
- Half-Life 2: Raising the Bar (As "prototype physics manipulator")
- Half-Life 2: Lost Coast (Non-canonical appearance)
- Half-Life 2: Episode One
- Source Particle Benchmark (Game files only) (Non-canonical appearance)
- Half-Life 2: Episode Two
- Portal 2: Lab Rat
- The Final Hours of Portal 2