The term Synth refers to a class of alien creatures that have been turned into war machines, and one of the several species that make up the Combine organization. They are officially described as "self-replicating robots that evolve", "created or taken over by the Combine and enslaved during their conquests and wars." Most Synths seem to possess both organic and robotic characteristics, suggesting that they may be the synthetic derivatives of sapient alien species that were previously enslaved by the Combine and assimilated into its armed forces.
Synths always appear as average to large insect-like or arthropod-like creatures, usually with segmented legs or antennae-like sensory structures, resembling locusts, crabs or similar beings.
It is unknown how many of the Synths presented in the series are 'true' to their initial species or forcefully evolved by the Combine, since the Combine modify their appearance by adding mechanical equipment and weaponry. It is also unclear whether they all come from the same planet (mirroring the Xen creatures that were also brought from other worlds and, for some of them, also enslaved). The Strider however, appears to have a brain, as seen in Episode Two. This is the only known Synth to possess any organ at all, however, other Synths likely possess one too.
The City 17 Citadel features factories where Synths are manufactured. For instance, Stalkers can be seen working on Gunships in the lower levels. Synths are also never observed to be "self-replicating" in-game, but seem to be raised and/or manufactured by the Combine.
Their carapace-like armor is largely immune to small arms fire (with the notable exceptions of the Hunter and Shield Scanner) and bullets striking it produce a metallic 'ping' noise. These outer shells can be ripped open with enough force, as demonstrated when Dog tears a Strider's head open in Episode Two. The only weapons that are known to be effective against the larger Synths are explosives (such as the RPG, the MP7's secondary fire, or the Magnusson Device) and the Combine Energy Ball.
Even though Synths posses organic characteristics, they are fully artificial, as their name suggests. However, they are shown to possess a brain, which is the only possibly organic feature they are known to possess. It is not known, however, whether it is a synthetic brain performing the functions of a brain, or if it is indeed organic.
Synths may or not have been used by the Combine during the Seven Hour War. Forces as the human-derived Combine units, such as Overwatch Soldiers, Hunter-Choppers, and APCs, would have only started appearing after the Combine rule on Earth had been established.
It is likely that the Combine forces used to invade earth were far more advanced than those stationed on earth, such forces being constituted of synths or not.
Various types of Synths have been brought over to Earth by the Combine, and more types of Synths probably exist elsewhere. Some, such as the Shield Scanner, are merely used as scouting or transport and have little to no weaponry, while others, such as the Strider, are fierce war machines. The known Synths are:
- Advisor Pod
- Combine Dropship
- Combine Gunship
- Crab Synth
- Mortar Synth
- Shield Scanner
Behind the scenes
- According to Dhabih Eng, the team tried to incorporate elements that were neither strictly organic nor purely mechanical to suggest their original organic forms. They did not want to have giant alien creatures with armor attached or implants added, but rather show a forceful evolution of the equipment unnaturally imposed on them by the Combine. In the end, the designs intentionally blurred the line between machine and animal, in their appearance and more importantly their motion and how they reacted to the world around them.
Several Synths were cut from the final game:
- Combine Guard (part-human, part-Synth)
- Combine Super Soldier
- Combine Synth Elite Soldier (part-human, part-Synth)
- Unidentified cut Synth
- Combine Mobile Mine
- Attack Synth
- Wasteland Scanner
Several pre-release materials gives some insight about the early Synths.
"Weather Control Vignette"
Raising the Bar features a story fragment of the Weather Control chapter given to the developers for design inspiration, relating parts of the Weather Control battle, with early names for the Combine units. For example "mech" seems to stand for the predecessors of the Synth, while "mech carrier" likely refers to the Combine Dropship. The text depicts the mech looking like Dog's cousins, but apparently new-minted and flawless, and with a "head" in quotes, suggesting that it is strangely-looking. Also, at some point in the text, its head pulses with a faint glow as if powering up for energy, then fires, which is very similar to the Strider's warp cannon, added to the fact that it is brought by a "carrier", the Strider being brought by Combine Dropships without their containers. Added to the gun located in its head, it also has mounted guns. This "mech" could be an early version of one the Synth predecessors of the Overwatch Elite, the Combine Synth Elite Soldier, which has been through several iterations with strangely-looking heads and a narrow waist like Dog (as in the picture seen here), or the Combine Super Soldier, also with a strangely-looking head.
A folder called "TBot1" can be found in the model textures files from the playable Half-Life 2 Beta files, in a folder called "obsolete". This is likely the textures for the early "mech" or (ro)bot from the Weather Control story fragment, a very early NPC, since it bears some similarities with Dog in design, mirroring the Weather Control story fragment covered above. Since Dog is said to be one of the few concepts that went from the first sketch straight into the game with relatively few changes to the design, it could be assumed that the Weather Control mechs are two legged and bear similar colors and same body part plates than Dog, since he was made from scraps from different metal sources, such as Combine metal (an old texture file for Dog also shows a "15" like logo also found in the TBot textures).
The textures also suggest a slightly battered robot, show round eyes that recall the City Scanner's eye, and therefore Dog's head, and is overall yellow-colored and seems to have paws-like feet and two legs, also like Dog. The model is however missing, and it is next to impossible to guess its shape from its texture files. The "1" in the folder's name also suggests that there was probably other versions, thus other colors or other conditions, for example ,non-battered textures. Other texture files suggest that it had an antenna and was equipped with a flamethrower and that some of its intern circuits were to be visible and blue, like the early Combine Dropship, the Crab Synth and the Mortar Synth. The files also suggest a "collar" made of green fabric, with the same fabric on one shoulder and the thighs, which seems peculiar, although it is another example of the old concept of the Combine recycling human materials.
This "TBot" ("bot" implying "robot") seems more mechanical than Synth (sporting several cogwheels and pistons on its bodywork), more in the "Combine recycling human materials" mood of the very early Half-Life 2 storyline and very closer to the "mech" from the Weather Control story fragment, therefore its model was likely an ancestor of the two-legged Synths of big size, the Combine Synth Elite Soldier or the Combine Super Soldier, with strangely-looking heads.
It's one of the variants of the TBot1, with green eyes, the colour of the robot is unknown, because the tbot in concept art is darked.
All his texture, model, sounds files were definitely deleted.
A story fragment from Raising the Bar is set at the start of the Air Exchange chapter and has Gordon involved in a train wreck when arriving there. Alyx encounters him with her pet Skitch and they are attacked by "tripods" (i.e. Striders) and "Combine Elite", tall shapes looking like metal, and with muffled, almost silent movements. That does fit the description of the Combine Super Soldier, named "Combine Elite" in Raising the Bar, while the Combine Synth Elite Soldier could also fit, since it was also to be an elite Combine unit. As also stated in the book, the Elite was turned into the humanoid unit seen in the final version.
LogosMost Synths bear at least one logo. Gunships and Striders bear the same logo on their back and head, respectively. This logo was on the back of the Overwatch Soldier's old texture (in white) and can also be seen on the shoulder of one of the Combine Synth Elite Soldier versions. Its meaning and whether it is a Combine logo or not or if it proves a closer relation between the Gunship and the Strider are unknown. Other Synths such as the Shield Scanner, the Dropship and the Advisor Pod bear the standard "claw" logo (in dark red for the two first ones and white for the latter), while the Shield Scanner also bears a trimmed "CMB" logo (like the City Scanner). The Mortar Synth, Crab Synth, and Hunter bear no logo at all.
As for the cut Synths, the Wasteland Scanner bears the standard "claw" logo (in dark Red), and other unknown markings, partially seen in the Overwatch Soldier outfit. The Combine Guard has no logo, while its predecessor, the Combine Synth Elite Soldier, has some informal logos in some of its versions, as well as the Gunships / Strider logo, as stated above. The Sacktick has two informal logos, one on its back, one on its right front leg, not seen elsewhere. The Combine Super Soldier has the number "314" in its concept art (also featured in the Beta Overwatch Soldier outfit), and two Red triangles in a Red-rounded circle, reused for the Overwatch Soldier outfit, although with different colors. It also has Red strips in several locations.
- The lack of organic matter when Synths explode suggest their robotical nature.
- The term "Synth" relates to words such as "synthetic", "synthesis" or "synthetical". A "synthetic" element is "made artificially by chemical synthesis"; a "synthesis" is "the combining of separate elements or substances to form a coherent whole"; and a "synthetical" element is the combination of "separate elements to form a coherent whole". The term "synth" could therefore be interpreted as a short for "synthetic".
- It could be argued whether Hunters are Synths or Cyborgs since they are vulnerable to gunfire and seem to have an integrated armor instead of a full metal body, unlike other Synths. A blood-like substance is observed on hit, also suggesting organic matter.
List of appearances
- Half-Life 2 (First appearance)
- Half-Life 2: Raising the Bar
- Half-Life 2: Episode One
- Half-Life 2: Episode Two